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Oil Change Interval - How Often?
- Thread starter plehrke
- Start date
zilik
VAF Moderator
Oil Change? You mean your suposed to change the oil?
Wow, news to me! I dump in a quart before every flight and change the filter every 200 hours or so.
Kidding aside, I was once in the oil @ 25 filter@ 50 hour camp. When I thought about this I reflected on the hundreds of oil changes in my autos and that I never skimped on a filter.
I changed my thinking to 25 hours oil and filter and If I miss it it's no big deal. So now my oil/filter changes fall somewhere between 25 and 35 hours. At about 30 hours the oil is starting to get darker than I like so I know it's about time to change.
I use aeroshell 20W-50 and buy Tempest filters by the 6-pack.
I like Flight Custom II's also and recently bought a 6-pack of them too.
Wow, news to me! I dump in a quart before every flight and change the filter every 200 hours or so.
Kidding aside, I was once in the oil @ 25 filter@ 50 hour camp. When I thought about this I reflected on the hundreds of oil changes in my autos and that I never skimped on a filter.
I changed my thinking to 25 hours oil and filter and If I miss it it's no big deal. So now my oil/filter changes fall somewhere between 25 and 35 hours. At about 30 hours the oil is starting to get darker than I like so I know it's about time to change.
I use aeroshell 20W-50 and buy Tempest filters by the 6-pack.
I like Flight Custom II's also and recently bought a 6-pack of them too.
cawmd82
Well Known Member
Positive loss lubrication....
You must be either a Brit or raised on a steady diet of Triumphs, BSAs and Nortons.
Wow, news to me! I dump in a quart before every flight and change the filter every 200 hours or so.
.
You must be either a Brit or raised on a steady diet of Triumphs, BSAs and Nortons.
Pilottonny
Well Known Member
50 hrs oil change sucks!
I am not flying yet, and I do assume the Spam cans of our club are maintained by the book. However, changing the oil every 50 hours (some change after 25 hours!) seem to me an unnecessary big burden on the environment and on our wallets!
Nowadays cars need an oil change between 20.000 km and 40.000 km!. At an average of 75 km/hr that is between 267 and 533 hrs.
15-20 years ago a friend of mine drove his Mercedes 240 TD (diesel) for 120.000 km without changing the oil, just adding some oil whenever necessary. After that he changed the oil and filter and sent a sample of the oil to a lab. Guess what? They told him the oil was still fine and could have been used further!
OK, we are flying, we can?t stop on the hard shoulder if we have a problem with the engine and we will probably run harder (more power) than an average car, but we will be adding a lot more new oil, due to the specifics of an air cooled engine. Why are we changing the oil at an equivalent of every 3.750 km (2.350 M)??? Even 30 years ago, the oil in cars was changed only after at least 5.000 km.
After engine break in, I am considering an oil change every 100 hrs, or ones a year. Maybe even more hours but not longer than a year.
Any comments please!
Regards, Tonny
I am not flying yet, and I do assume the Spam cans of our club are maintained by the book. However, changing the oil every 50 hours (some change after 25 hours!) seem to me an unnecessary big burden on the environment and on our wallets!
Nowadays cars need an oil change between 20.000 km and 40.000 km!. At an average of 75 km/hr that is between 267 and 533 hrs.
15-20 years ago a friend of mine drove his Mercedes 240 TD (diesel) for 120.000 km without changing the oil, just adding some oil whenever necessary. After that he changed the oil and filter and sent a sample of the oil to a lab. Guess what? They told him the oil was still fine and could have been used further!
OK, we are flying, we can?t stop on the hard shoulder if we have a problem with the engine and we will probably run harder (more power) than an average car, but we will be adding a lot more new oil, due to the specifics of an air cooled engine. Why are we changing the oil at an equivalent of every 3.750 km (2.350 M)??? Even 30 years ago, the oil in cars was changed only after at least 5.000 km.
After engine break in, I am considering an oil change every 100 hrs, or ones a year. Maybe even more hours but not longer than a year.
Any comments please!
Regards, Tonny
islandmonkey
Well Known Member
Chuck, geezer, are you having a pop at us Brits? D'ya know wot I mean.
Old Harleys and Indians leak just as much if not more!!
RV7Guy
Well Known Member
25 hrs filter/oil
I change both every 25 hours give or take an hour or two. I fly in harsh conditions. It will be 110 when I leave for work today!!! I feel that oil and filters are very cheap insurance. I try to find oil at a discount and buy the filters by the six pack. (Philips XC and Kelly filters).
Interestingly, I burn less than a quart of oil per 25 hours. More like a half quart. I guess if you flew in less harsh conditions you could get away with increased hours.
Now, if I could by the oil buy the drum, I'd do so and get a few guys together to share the expense. Apparently Philips XC isn't offered in drum quantities.
I change both every 25 hours give or take an hour or two. I fly in harsh conditions. It will be 110 when I leave for work today!!! I feel that oil and filters are very cheap insurance. I try to find oil at a discount and buy the filters by the six pack. (Philips XC and Kelly filters).
Interestingly, I burn less than a quart of oil per 25 hours. More like a half quart. I guess if you flew in less harsh conditions you could get away with increased hours.
Now, if I could by the oil buy the drum, I'd do so and get a few guys together to share the expense. Apparently Philips XC isn't offered in drum quantities.
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Rick6a
Well Known Member
Russ McCutcheon
Well Known Member
Using Exxon Elite 20-50, changing the oil every 40 to 50 hours and filter every other time or 80 to 100 hours (oil change about every two months), Oil burn is on the order of a quart every 15 hours, always check for metal in the filter, never more then a couple of specks and the oil analyst each year is always very low.
100 hour oil changes? I bet it will work but after over hauling a 1000 hour engine that had 50 hour oil changes and seeing the amount of lead sludge I would not go past 50 hours for oil changes, seems the oil is not suspending all the lead, the unsuspended lead is left as sludge. I would think the fresher you keep the oil the less sludge will be left in the engine. Un-leaded fuel might be a different story.
100 hour oil changes? I bet it will work but after over hauling a 1000 hour engine that had 50 hour oil changes and seeing the amount of lead sludge I would not go past 50 hours for oil changes, seems the oil is not suspending all the lead, the unsuspended lead is left as sludge. I would think the fresher you keep the oil the less sludge will be left in the engine. Un-leaded fuel might be a different story.
Bryan Wood
Well Known Member
30 for me, filter and oil
My engine has a predictable trend after an oil change. For a given number of hours the mark on the dipstick that the oil makes shows no movement. Somewhere above 10 hours, but closer to twelve it gets thirsty and consumes oil. It'll rid itself of a quart pretty quickly after this point and when I put one in it will need another in 4 hours or so. I'll put that one in and it'll need another in 4 or 5 hours. At that point there is no need to carry oil in the baggage area or to even check it because it will not move until 30 hours is up and I drain it. My father in laws IO-540 Lyc has a similar pattern. These engines seem to be tough on oil. Anybody else have similar trends?
My engine has a predictable trend after an oil change. For a given number of hours the mark on the dipstick that the oil makes shows no movement. Somewhere above 10 hours, but closer to twelve it gets thirsty and consumes oil. It'll rid itself of a quart pretty quickly after this point and when I put one in it will need another in 4 hours or so. I'll put that one in and it'll need another in 4 or 5 hours. At that point there is no need to carry oil in the baggage area or to even check it because it will not move until 30 hours is up and I drain it. My father in laws IO-540 Lyc has a similar pattern. These engines seem to be tough on oil. Anybody else have similar trends?
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L.Adamson
Well Known Member
I run my Lycoming 0360 at six quarts. If I use more, it spits it out. At six quarts, consumption is low. I know of many others that do the same.
L.Adamson --- RV6A
Bryan Wood
Well Known Member
Ditto, from the very first flight. By that I mean that I put in seven quarts after a change and after startup one gets lost in the filter and or cooler?. So six on the dipstick is where I keep it. Are you saying you keep yours at 5 on the dipstick and only put in 6 quarts? Where do others keep their oil on the dipstick?
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RBD
Well Known Member
Tony, as I understand it, the concern is that with our "loose" air-cooled engines, a lot more bad stuff (i.e. unburnt fuel, combustion gases, acids, water vapor, etc...) ends up in our oil than in the oil of an automobile engine. If it were strictly a matter of the oil breaking down, our oil change intervals would be much greater. Getting the bad stuff out is a good thing.
L.Adamson
Well Known Member
Jamie
Well Known Member
I don't understand the obsession with changing oil every 25 hours. I guess people do it because it "feels" right, but after extensive reading, research and asking many knowledgeable people I cannot find any official recommendation anywhere that oil be changed every 25 hours when using an oil filter. If you have no oil filter 25 hour changes are appropriate.
Does someone have information to the contrary?
Also, it never makes any sense to talk about how much oil you burn unless you talk about how much you put it to begin with! As has already been mentioned, most 4 banger Lyclones will burn/leak much less oil at 6 quarts than at 8.
Does someone have information to the contrary?
Also, it never makes any sense to talk about how much oil you burn unless you talk about how much you put it to begin with! As has already been mentioned, most 4 banger Lyclones will burn/leak much less oil at 6 quarts than at 8.
Jamie
Well Known Member
Webb: You and I must think alike. I do the same thing.
turbo
Well Known Member
oil is cheap
my routine is 30 hrs drain oil and send out sample. i can run a hose up the lower cowl and connect to a quick drain. at 60 hrs i change oil and filter and cut open filter. the 30 hrs hobbs time figures out to be 25 hrs flying time. thats over 4,000 miles, used 2 qts oil, running it with 6 qts added. a 1/2 qt marvel is mixed in with the oil. FLY A LOT. OIL IS CHEAP.
my routine is 30 hrs drain oil and send out sample. i can run a hose up the lower cowl and connect to a quick drain. at 60 hrs i change oil and filter and cut open filter. the 30 hrs hobbs time figures out to be 25 hrs flying time. thats over 4,000 miles, used 2 qts oil, running it with 6 qts added. a 1/2 qt marvel is mixed in with the oil. FLY A LOT. OIL IS CHEAP.
Rick6a
Well Known Member
Jamie,
Some of us may not necessarily consider it an "obsession" to change the oil every 25 hours. Oil is (relatively cheap) insurance. I cannot speak for others but nothing in this life is permanent. Nobody can predict the future. At some unknown point like everybody else in this life, I will eventually endure change in whatever form that may take. I'm sure that among other things, a logbook documenting a routine 25 hour oil change would be noteworthy detail any potential buyer would find desirable and suggestive of a well maintained aircraft whether or not that potential buyer personally agrees with a 25 hour oil change philosophy or not.
Jamie
Well Known Member
Hi Rick:
Thanks for the reply.
What are you insuring against? I guess that's my question. I'm open-minded here and am always eager to learn. My personal belief is that 25 hour changes are a hold-over from the pre-spin on oil filter days. But hey, whatever makes people feel comfortable is fine with me.
Jamie
Thanks for the reply.
What are you insuring against? I guess that's my question. I'm open-minded here and am always eager to learn. My personal belief is that 25 hour changes are a hold-over from the pre-spin on oil filter days. But hey, whatever makes people feel comfortable is fine with me.
Jamie
Pilottonny
Well Known Member
50 hrs seems to be the limit?
OK, so far nobody goes over the +/- 50 hrs oil change. What if you are burning mogas (what I am planning to do)? There is no lead to accumulate, so 100 hrs should be OK?
Also I wonder if the quality of "car oil" is way ahead of "aviation oil"?
Normally the exhaust valves of a Lexus will never be touched, but because I am running LPG (Liquified Petroleum Gas) in my RX300 and this burns a lot hotter than gasoline, the valve gaps have to be set at an interval of about 40.000 km. When the garage was doing this, I had a chance to look inside the engine: looks like brand spanking new after 280.000 km! The oil that was in there for over 20.000 km looked exactly the same as the new oil they put in. (they say I should have it changed every 15.000 km!.... yeah right because they make more money that way!) Actually I am thinking of never changing the oil again, till the car quits. let's see how long that will take.
Still looking for people that dare to go longer than 50 hrs, and their comments. I have no idea what the price of aviation oil is, since I have not had to buy any, but throwing away 6 or even 8 liters (quarts) of perfectly good oil (if it is still good after 50 hrs) seems to me like a waste and bad for the environment.
Regards, Tonny.
OK, so far nobody goes over the +/- 50 hrs oil change. What if you are burning mogas (what I am planning to do)? There is no lead to accumulate, so 100 hrs should be OK?
Also I wonder if the quality of "car oil" is way ahead of "aviation oil"?
Normally the exhaust valves of a Lexus will never be touched, but because I am running LPG (Liquified Petroleum Gas) in my RX300 and this burns a lot hotter than gasoline, the valve gaps have to be set at an interval of about 40.000 km. When the garage was doing this, I had a chance to look inside the engine: looks like brand spanking new after 280.000 km! The oil that was in there for over 20.000 km looked exactly the same as the new oil they put in. (they say I should have it changed every 15.000 km!.... yeah right because they make more money that way!) Actually I am thinking of never changing the oil again, till the car quits. let's see how long that will take.
Still looking for people that dare to go longer than 50 hrs, and their comments. I have no idea what the price of aviation oil is, since I have not had to buy any, but throwing away 6 or even 8 liters (quarts) of perfectly good oil (if it is still good after 50 hrs) seems to me like a waste and bad for the environment.
Regards, Tonny.
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tc1234c
Well Known Member
I change oil and filter at 50 hr hobbs and does oil analysis every 100 hrs. I add 6 qts new oil at oil change time. When the level drop below 5 I add another qt. I used to add 3 qt but now 2 qt between oil changes. After 613 hrs (hobbs) my oil analysis shows a trend of less metals. Just did a compression test, all four are above 76/80. Except #1 dropped from 79 to 76, the rest are about the same as factory new. I am no expert on engine and have nothing else to judge how well my engine runs (holding up).
JonJay
Well Known Member
It's only a recommendation....
I changed my unfiltered L3's oil at 25 hours, by my watch - why? No tach, no hobbs, so that is what I had to go by.
I change my oil in my Bucker every 50 hours tach - why? That is what my recording tach gives me. The 0320 in my Bucker has always had 50 hour changes. 2200 hours and still going strong.
I change my RV6 every 50 hours Hobbs - why? That is what my EMS gives me. 220 hours going for 2200 plus. I like my odds.
I changed my unfiltered L3's oil at 25 hours, by my watch - why? No tach, no hobbs, so that is what I had to go by.
I change my oil in my Bucker every 50 hours tach - why? That is what my recording tach gives me. The 0320 in my Bucker has always had 50 hour changes. 2200 hours and still going strong.
I change my RV6 every 50 hours Hobbs - why? That is what my EMS gives me. 220 hours going for 2200 plus. I like my odds.
Russ McCutcheon
Well Known Member
When you start flying your airplane you will find I suspect even with unleaded fuel that your oil, un-like in your car does not look new after 50 hours. Your car engine is the same but also very different from your Lycoming, the car has smaller cylinder bores and a much smaller operating temp range as a result the car engine can have much less clearance between piston and cylinder as well as much tighter ring end gaps, the barriers between the ?top? and the oil are much more affective in your car engine, not to mention cylinder pressure is most often much lower in that care loafing along. Long story short your Lycoming will transfer a lot of combustion gasses/material into the oil. You will figure it out when you get started flying.
Preventative Inspections
I have also found that taking the cowl off ever 50 hours for oil changes is a reason to give the firewall forward a good once over. Lots of things you could find with a quick look-see while the oil is draining before they may become catastrophic. Just like they say for health care, preventive maintenance pays for it self in the long run.
I have also found that taking the cowl off ever 50 hours for oil changes is a reason to give the firewall forward a good once over. Lots of things you could find with a quick look-see while the oil is draining before they may become catastrophic. Just like they say for health care, preventive maintenance pays for it self in the long run.
There is a lot of info on the net about oil degredation. The quote from one of those below probably sums it up best about dark oil. The article also made the comment that to change oil early was common to recreational oil changers.
Probably what is most important is what you do after the oil change, not how often and that is verify your engine isn't making metal IMHO.
*****************************
The Dark Oil Myth
Dark oil does not indicate the need for an oil change. The way modern detergent motor oil works is that minute particles of soot are suspended in the oil. These minute particles pose no danger to your engine, but they cause the oil to darken. A non-detergent oil would stay clearer than a detergent oil because all the soot would be left on the internal engine parts and would create sludge. If you never changed your oil, eventually the oil would no longer be able to suspend any more particles in the oil and sludge would form. Fortunately, by following the manufacturer's recommended oil change interval, you are changing your oil long before the oil has become saturated. Remember, a good oil should get dirty as it does it's work cleaning out the engine. The dispersant should stop all the gunk from depositing in the oil pan.
Probably what is most important is what you do after the oil change, not how often and that is verify your engine isn't making metal IMHO.
*****************************
The Dark Oil Myth
Dark oil does not indicate the need for an oil change. The way modern detergent motor oil works is that minute particles of soot are suspended in the oil. These minute particles pose no danger to your engine, but they cause the oil to darken. A non-detergent oil would stay clearer than a detergent oil because all the soot would be left on the internal engine parts and would create sludge. If you never changed your oil, eventually the oil would no longer be able to suspend any more particles in the oil and sludge would form. Fortunately, by following the manufacturer's recommended oil change interval, you are changing your oil long before the oil has become saturated. Remember, a good oil should get dirty as it does it's work cleaning out the engine. The dispersant should stop all the gunk from depositing in the oil pan.
NOT DETERGENT!
Every time I go to an engine or oil seminar, including this last weekend at Arlington, they make the same point that we DO NOT USE detergent oil in aircraft. We use AD oil that disperses the particles picked up in the oil so that they can be removed by the filter.
See the following by Harold Tucker, Lubricants Technical Director for the Phillips 66 Company; Dr. Alex Schuettenberg, Senior Research Chemist, Lubricants Technical Support for Phillips 66; and by Richard Fowler, President of America’s Aircraft Engines, Inc.
10. No detergents are ever added to aviation oils.
There is no such thing as an aviation oil that contains detergents. Aviation oils have not contained detergent packages since the mid-1950s. Single and multiviscosity grade mineral-based oils instead contain ashless dispersant (AD) additive packages. ADs are very different than detergents:
• ASHLESS refers to non-metallic additives. Detergents, on the other hand, are metallic by nature. Detergents may scrub existing ash deposits from an engine’s interior surfaces, which will contribute to the ash content, and possible clogging, of the oil.
• DISPERSANT refers to the oil’s ability to suspend combustion by-products, keeping them dispersed until the oil is drained.
Because they suspend engine by-products, AD oils darken faster than non-AD oils. This is a sign that the oil is preventing by-products from solidifying on interior engine surfaces. All AD aviation oils contain oxidation inhibitors as part of their standard additive chemistry. AD oils will not dislodge quantities of sludge from interior engine surfaces that lead to restricted oil screens. AD oils do not add deposit build-up. Instead, they help dissipate existing by-products over time. For example, if an operator uses a non-AD oil for 500 hours, then switches to an oil with an AD package for 500 hours, the AD oil will not "clean out" the first 500 hours worth of engine deposits.
Every expert I've talked to or read says the more often the better and it's cheap ($50) insurance, meaning makes your engine (say $15,000 to $35,000) last longer. Seems those that want to argue don't have these in depth qualifications and are relatively new to this arena with possibly more experience in auto motors with much different operations and needs. And yes, clearly most autos do not need 3000 mile changes - I know.
My oil analyses shows much cleaner and more effective oil when changed more often. Almost 2000 hours on an engine rebuilt in 1976 and still going strong (but flying a LOT more often now days......).
Why argue with that?
Every time I go to an engine or oil seminar, including this last weekend at Arlington, they make the same point that we DO NOT USE detergent oil in aircraft. We use AD oil that disperses the particles picked up in the oil so that they can be removed by the filter.
See the following by Harold Tucker, Lubricants Technical Director for the Phillips 66 Company; Dr. Alex Schuettenberg, Senior Research Chemist, Lubricants Technical Support for Phillips 66; and by Richard Fowler, President of America’s Aircraft Engines, Inc.
10. No detergents are ever added to aviation oils.
There is no such thing as an aviation oil that contains detergents. Aviation oils have not contained detergent packages since the mid-1950s. Single and multiviscosity grade mineral-based oils instead contain ashless dispersant (AD) additive packages. ADs are very different than detergents:
• ASHLESS refers to non-metallic additives. Detergents, on the other hand, are metallic by nature. Detergents may scrub existing ash deposits from an engine’s interior surfaces, which will contribute to the ash content, and possible clogging, of the oil.
• DISPERSANT refers to the oil’s ability to suspend combustion by-products, keeping them dispersed until the oil is drained.
Because they suspend engine by-products, AD oils darken faster than non-AD oils. This is a sign that the oil is preventing by-products from solidifying on interior engine surfaces. All AD aviation oils contain oxidation inhibitors as part of their standard additive chemistry. AD oils will not dislodge quantities of sludge from interior engine surfaces that lead to restricted oil screens. AD oils do not add deposit build-up. Instead, they help dissipate existing by-products over time. For example, if an operator uses a non-AD oil for 500 hours, then switches to an oil with an AD package for 500 hours, the AD oil will not "clean out" the first 500 hours worth of engine deposits.
Every expert I've talked to or read says the more often the better and it's cheap ($50) insurance, meaning makes your engine (say $15,000 to $35,000) last longer. Seems those that want to argue don't have these in depth qualifications and are relatively new to this arena with possibly more experience in auto motors with much different operations and needs. And yes, clearly most autos do not need 3000 mile changes - I know.
My oil analyses shows much cleaner and more effective oil when changed more often. Almost 2000 hours on an engine rebuilt in 1976 and still going strong (but flying a LOT more often now days......).
Why argue with that?
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andrew phillips
Well Known Member
my thoughts
I change about every 50 hrs. I used to be an oil change nut on other vehicles in my younger days. I even flushed the crankcase with oil before putting in the "real" oil. Then I got to thinking about it.
I worked in a garage in my youth. I never saw an engine come in with oil related failure. I saw lots of accessory failures but hardly ever the main bearings or cylinder walls or lifters or cams or the other places where the oil was doing all the work. I did have a motorcycle that lost a main bearing once but it turned out that the engine had a flaw and lots of these engines lost the same bearing so it was hardly the oils fault when all the rest of the bearings were still good. One lady had never changed her oil since her husband died years earlier. It didn't even look like oil but the old Caddy kept on running.
I think deep down we think of our engines in human terms. We feel good when we know they are clean and freshly lubricated just like ourselves . How many people feel like their cars run better when they are freshly washed?
I am sure that there are some good reasons to change oil frequently with respect to some of the rust inhibiting properties or other things that chemical engineers could enlighten me on. I think my plane could run a lot longer on the oil than the 50 hour intervals I go by but I do like looking at that golden color on the dipstick. Oh well, guess I am like everybody else.
I change about every 50 hrs. I used to be an oil change nut on other vehicles in my younger days. I even flushed the crankcase with oil before putting in the "real" oil. Then I got to thinking about it.
I worked in a garage in my youth. I never saw an engine come in with oil related failure. I saw lots of accessory failures but hardly ever the main bearings or cylinder walls or lifters or cams or the other places where the oil was doing all the work. I did have a motorcycle that lost a main bearing once but it turned out that the engine had a flaw and lots of these engines lost the same bearing so it was hardly the oils fault when all the rest of the bearings were still good. One lady had never changed her oil since her husband died years earlier. It didn't even look like oil but the old Caddy kept on running.
I think deep down we think of our engines in human terms. We feel good when we know they are clean and freshly lubricated just like ourselves . How many people feel like their cars run better when they are freshly washed?
I am sure that there are some good reasons to change oil frequently with respect to some of the rust inhibiting properties or other things that chemical engineers could enlighten me on. I think my plane could run a lot longer on the oil than the 50 hour intervals I go by but I do like looking at that golden color on the dipstick. Oh well, guess I am like everybody else.
The full article David quoted above:
http://www.swaviator.com/html/issueja02/Hangar7802.html
The distinction between "detergent" and "dispersant" is subtle, and although important to full understanding it is probably not very germane to change interval.
We change oil to remove suspended dirt, acids, water, etc, not because the base oil has lost its ability to lubricate. I'll venture to say the "correct" oil change interval has a lot more to do with operator habits and operating conditions than any form of hour measurement.
http://www.swaviator.com/html/issueja02/Hangar7802.html
The distinction between "detergent" and "dispersant" is subtle, and although important to full understanding it is probably not very germane to change interval.
We change oil to remove suspended dirt, acids, water, etc, not because the base oil has lost its ability to lubricate. I'll venture to say the "correct" oil change interval has a lot more to do with operator habits and operating conditions than any form of hour measurement.
Question for those that have their oil analized.....if it can be answered.
When you changed your oil, what percentage of life did the oil still have?
For example....if changed at 50 hours, the oil still had ## percentage of life left. My wife's car has a % meter on it for oil and tells us when it should be changed. The mileage varies between changes.
I'm wondering if there is a bit more of a scientific way of knowing instead of just changing by the clocked hours.
When you changed your oil, what percentage of life did the oil still have?
For example....if changed at 50 hours, the oil still had ## percentage of life left. My wife's car has a % meter on it for oil and tells us when it should be changed. The mileage varies between changes.
I'm wondering if there is a bit more of a scientific way of knowing instead of just changing by the clocked hours.
David-aviator
Well Known Member
Back in 1993, the year of the great St. Louis flood, there was a guy who had an experimental airplane at KSET. The airport was under 6-8 feet of water for several months and so was his airplane. When things got back to normal, I heard this guy drained the oil/water from the engine, separated the two and poured the oil back into the engine.
It's all a matter of how frugal (cheap) an individual is. I suppose dirty oil could be cleaned up with filters and used again. I don't know.
By the way, I don't think that airplane flew again, but I know the guy was thinking about it as he was a brave soul, but I don't think he flew it. I believe it was moved to Tennessee on a truck.
The computer on your wife's car is not all that scientific. It simply looks at the way you drive. i.e. short trips vs. long trips, etc. If used mostly for long trips where the oil has time to get good and hot, the oil can go longer between changes. It does not analyze the oil.
