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bjb3013

Well Known Member
How warm should I let my oil ,CHT, etc. get before run up or takeoff.
I am not talking about preheat. On a 38 degree day it takes a while at 1000 rpm or less to get the oil temp to my 120 degree personal limit that I picked out of thin air. Is this reasonable? Naturally it warms up quickly in flight but what is the minimum I should see before takeoff.
 
Generally oil is in the "green" at about 75 degrees. If your oil gauge isn't marked, the bottom of the green is right at 75 or 80 degrees. Good to go from there. Depending on your CHT gauge, those temps may not even register until you get off the ground and get the engine turning some RPM's.
 
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Also depends on what grade of oil you use. Around here in "sunny SoCal," the temps can start out around 35F in the morning and hit 70F by mid-day. That's why I splurge for Aeroshell 15W50. I probably sound like a commercial and I'm a sucker for their marketing, I guess, but I like how it "acts" like a thinner oil when cold and like a thicker oil when hot.

The other day I was sitting at the run-up area up in Palo Alto waiting for my oil to warm up before doing the run-up. It hit 65F and I figured...highly doubt the prop will cycle...but it did. Not sure if a straight weight oil would do that.

As a rule I don't take off until the oil temp reaches 100F, but the magic-ness and roundness of that number is somewhat arbitrary. I don't think the thing is gonna explode if you go balls to the wall at 99.2F. Know whaddamean?
 
I've been using the magic "100" number as well, but that has no scientific value whatsoever....I'm using Elite multi-vis....the prop cycles fine at 80 degrees....I'd love to hear from someone who has data on oil temp versus engine wear!

Paul
 
Can't get temp up!

I can barely get my oil temp off of the peg before run up. In the winter I can't get it past 150. Ever. Even in the summer I have a difficult time getting it to 180. I have a shutter on the oil cooler which I almost always run shut. It only seems to make a difference on the hottest days.
 
I too have been using 100 degrees, but...

Lycoming in their Key Reprints says:

PREVENT POWER LOSS ON TAKEOFF WITH DIRECT DRIVE ENGINES IN COLD WEATHER

In cool or cold weather, pilots should take extra care prior to attempting to takeoff with a cold engine and cold oil, and thereby prevent a temporary power loss during a critical part of the takeoff. Cold or heavy oil can and quite often does affect normal operation of the hydraulic lifters. Remember that aviation lubricants are heavier when cold than the commonly used automotive engine oils and require a little more time in warm-up to obtain normal flow in order to function properly throughout the air cooled aircraft engine.

To prevent possible power loss, a proper warm-up should be conducted. The engine is usually warm enough for pre-flight ground check in above freezing temperatures after 2 to 3 minutes running at 1000 to 1200 RPM. Below freezing temperatures, the warm-up period should be longer. With turbocharged powerplants, cold oil and cold engines require a longer warm-up period to assure proper controller operation and to prevent manifold pressure overboost.

After the above recommended warm-up period in cool or cold weather, including magneto and runup check, if the oil pressure is consistently over maximum red line, have a knowledgeable mechanic adjust oil pressure so that it does not exceed red line at takeoff or climb powers, and yet it is within the recommended green arc area at cruise. Cold weather tends to require a longer warm-up period.

Another cause of the power loss under these temperature and flight conditions has been the use of a heavier weight viscosity of oil than recommended for the ambient temperature flight condition. A heavier weight oil than recommended in cool or cold weather will tend to prevent the normal operation of the hydraulic lifters and thereby cause a loss of power.

Thus, to prevent power loss on takeoff with direct drive engines, select the proper weight oil for your engine for cold weather operation Make a careful run-up prior to takeoff with cold oil and a cold engine and observe engine instruments. Extend your warm-up period in cold weather until oil pressure is within recommended limits, or consult a mechanic concerning a compromise adjustment. If in doubt about power output, a brief smooth full throttle check is recommended.


In another section they also mention that in cold weather that you should never idle below 1000 rpm.

Kent

Kent
 
cjensen said:
Generally oil is in the "green" at about 75 degrees. If your oil gauge isn't marked, the bottom of the green is right at 75 or 80 degrees. Good to go from there. Depending on your CHT gauge, those temps may not even register until you get off the ground and get the engine turning some RPM's.
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Where did you get that info from? I personally think 100 degrees F should be the minimum.
Sceptical
Tom
RV3
 
MXpilot1 said:
I can barely get my oil temp off of the peg before run up. In the winter I can't get it past 150. Ever. Even in the summer I have a difficult time getting it to 180. I have a shutter on the oil cooler which I almost always run shut. It only seems to make a difference on the hottest days.
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You might want to calibrate that guage. Put it in fast boiling water for approx. 212F.
 
tin man said:
Where did you get that info from? I personally think 100 degrees F should be the minimum.
Sceptical
Tom
RV3
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The Lycoming manual says 75-80 if I remember right. That's what I use, but 20 degrees is not worth arguing about. What ever works for you.
 
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kentb said:
Lycoming in their Key Reprints says: In another section they also mention that in cold weather that you should never idle below 1000 rpm.
Kent
Click to expand...

Very interesting. I have been idling in the 850-900 rpm range while the oil warms. I guess I will accept Lycomings recommendation.

I will generally idle at my starting location until the oil reaches 75 F and then taxi to the runway. I will then wait for 95 F before doing my engine run-up and then depart asap.

Karl.
 
I normally idle the engine at 1000 rpm untill the oil temp is above 80 d f then push the idle up to 1200. When the oil temp is up to 100 degrees f I do my run up and by the time I am lined up for take off it is ususally up to at least 120. No science here -- I just feel better doing it this way. Any engine experts have any advice?? Mahlon are you out there??

Cheers,

Dave B.
RV9a/ECi0360/James cowl/Catto prop--105+ hrs and a permanent smile
 
Preheat

Guys,
It's so inexpensive to do it right. While you're waiting for your oil to heat up, the cylinders could very well be getting too hot. With a simple, under $200 preheater, you can have 100 deg. oil when the prop first turns and save a lot of engine wear because of the lousy lubricating properties of cold oil. Click this link. It takes less than an hour to install.
http://www.reiffpreheat.com/

Regards,
 
Oil Temp

I let mine warm up to 100, which as everyone else indicates is arbitrary, but that seems to be the magic number to prevent too high of an oil pressue on take-off. If I take off with it 90 or less, my oil pressure warning goes off when departing. At around 85-90, I'll do a runup and mag check and that is usually enough to get it heading toward 100 a little quicker.
 
95 is go for me with straight grade Aeroshell 100. Subjective number but it has served me very well for 900-hrs. Thinking about how oil get's to the rockers makes me very leery of going with cold oil.

In the environments I fly in and with my equipment, I never see excessive CHTs while waiting on the oil to warm.

2 cents
 
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