Can I use Mobil 1 oil?

[jim etcheverry]

ok for the tech. talk. The car oil have ash used mainly for detergent purposes. This under high temps can form carbon. This could happen in turbo charged engines and really only in our non-turbo when descending and forgetting to richen the mixture. Thus ashless dispersents, keep dirt in solution and drain off. As far as the high ZINC there are today many oil made with what they call high Zinc use for flat tappet engines, but it really is the old level of zinc used before the roller tappet. They say right on the bottle. Eaa has a nice video from Mike Bush well done on oil to explain everything about aviation oil.http://eaavideo.org/video.aspx?v=1149666747001. Long but great. You need to get to the TD sheet for the exact oil and look at the ash by wt.% and you'll find 1.2 to 1.6 for most of these oil. Mobil 15/50 http://pds.mobil.com/USA-English/Lub...l1_15W-50.aspx check out application ( Not for 2 cycle or aviation engines) also the ash content. You are right lead will be gone and even Mike Bush says when lead is gone it is time to look at synthetics. So this question in a valid question when lead is gone. Soon or Sooner.

[BillL]

Originally Posted by rv7charlie

Interesting that one of the downsides is lack of shear strength (assuming that it actually applies to synthetics) on flat tappet cams. The rotary a/c engine guys using RWS gear drives use synthetic engine oil specifically because it seems to provide smoother, quieter operation of the gearbox (engine oil lubes the plain bearing, and the planetary gearset, in the gearbox).

Charlie

Unfortunately to the OP, I don't have any DATA.

But to the quoted post: It is what is called boundary lubrication - like gear contact in crawler tractors (and such) with low shear rates but high contact pressures. The ZDP is like magic little ball bearings. Once in my research job I had some super gear/lube experts working for me to develop oils for that purpose (gear box not engine) and they would try dozens of formulations with various test machines for spot wear. It is not an analytical thing. Materials, hardness, surface finishes and the additive packages are all factors. All lubricants are a compromise according the the functions and applications for them.

Don't you think Shell, and others, are already testing additive packages/oils for the non-leaded fuels to understand what they can do? Cams, ring grooves, valve stems/guides all have special needs.

Wouldn't it be great to use an oil that didn't varnish and didn't contribute to exhaust valve sticking, and lasted longer hours? Yes, of course.

Good search Bret!!

[lr172]

Originally Posted by rv7charlie

Interesting that one of the downsides is lack of shear strength (assuming that it actually applies to synthetics) on flat tappet cams. The rotary a/c engine guys using RWS gear drives use synthetic engine oil specifically because it seems to provide smoother, quieter operation of the gearbox (engine oil lubes the plain bearing, and the planetary gearset, in the gearbox).

Charlie

Gear tooth interface presents different wear factors than the cam/lifter interfaces. There is an insignificant amount of sliding or shear between the teeth. It's all pressure, not shear. With cam/lifter, it's both.

[rv6ejguy]

I had a customer ask me this question years ago. He switched to 15/50 Mobil 1 in his Lycoming and had over 800 hours on it last time I heard about 4 years ago. No issues. He was using Mogas locally and 100LL for cross country work. Changed oil every 30-50 hours depending on the amount of 100LL put through the engine.

Not sure if he had flat or roller lifters.

The trend in auto engines over the last 10 years has been to use thinner oils to reduce internal drag and flow between the reduced clearances. 0/20 is common now.

Not sure if I buy the low zinc thing. I've used Mobil 1 since the early '80s (many different formulations in that time) in many race engines with flat tappets and very high spring pressures along with most of my street engines. Never had one lubrication related issue in all that time and we're talking many dozens of engines, many thousands of hours and mostly turbocharged which is very trying on oils thermally and load wise.

I ran Mobil 1 in my Subaru turbo RV6 for 250 hours running 100LL exclusively. When I pulled the pan, there were no lead deposits anywhere, super clean inside. Changes were at 30-40 hours. There were massive lead buildups on everything inside the chambers and turbine though due to the lower temperatures the liquid cooled engine operates at here.

Changed frequently, like every 25 hours, I don't think lead is a big issue with Mobil 1 if your ring seal is decent but given the price of it, draining it so often seems like a waste at the same time. Lycomings generally seem to last well using Aeroshell, so not sure there is a big advantage there until the fuels go unleaded and you can leave it in a lot longer.

Rotax halves the oil change intervals when operated on 100LL exclusively compared to Mogas. One overhauler told me engines with a steady 100LL diet
were usually pretty gunked up in the oil tank and gearbox with lead if people did not follow this advice.

I believe you will see new synthetic aero oils on the market when unleaded avgas is available. Full synthetics are really magic in gearboxes and race engines. Things last which won't last using conventional oils. Whether that translates into big advantages on Lycomings though is hard to say.

[bret]

Originally Posted by rv6ejguy

I had a customer ask me this question years ago. He switched to 15/50 Mobil 1 in his Lycoming and had over 800 hours on it last time I heard about 4 years ago. No issues. He was using Mogas locally and 100LL for cross country work. Changed oil every 30-50 hours depending on the amount of 100LL put through the engine.

Not sure if he had flat or roller lifters.

The trend in auto engines over the last 10 years has been to use thinner oils to reduce internal drag and flow between the reduced clearances. 0/20 is common now.

Not sure if I buy the low zinc thing. I've used Mobil 1 since the early '80s (many different formulations in that time) in many race engines with flat tappets and very high spring pressures along with most of my street engines. Never had one lubrication related issue in all that time and we're talking many dozens of engines, many thousands of hours and mostly turbocharged which is very trying on oils thermally and load wise.

I ran Mobil 1 in my Subaru turbo RV6 for 250 hours running 100LL exclusively. When I pulled the pan, there were no lead deposits anywhere, super clean inside. Changes were at 30-40 hours. There were massive lead buildups on everything inside the chambers and turbine though due to the lower temperatures the liquid cooled engine operates at here.

Changed frequently, like every 25 hours, I don't think lead is a big issue with Mobil 1 if your ring seal is decent but given the price of it, draining it so often seems like a waste at the same time. Lycomings generally seem to last well using Aeroshell, so not sure there is a big advantage there until the fuels go unleaded and you can leave it in a lot longer.

Rotax halves the oil change intervals when operated on 100LL exclusively compared to Mogas. One overhauler told me engines with a steady 100LL diet
were usually pretty gunked up in the oil tank and gearbox with lead if people did not follow this advice.

I believe you will see new synthetic aero oils on the market when unleaded avgas is available. Full synthetics are really magic in gearboxes and race engines. Things last which won't last using conventional oils. Whether that translates into big advantages on Lycomings though is hard to say.

That is some good believable data, thanks for the input. A point made in the vid post 1 there was mention of the turbo guys like the synthetic also. does anyone have any data comparison as far as max temperature before the oil burns or chars into ash?

[rv6ejguy]

Originally Posted by bret

That is some good believable data, thanks for the input. A point made in the vid post 1 there was mention of the turbo guys like the synthetic also. does anyone have any data comparison as far as max temperature before the oil burns or chars into ash?

I looked at the manufacturer's data about 6-7 years ago and the Aeroshell was only about 30-40 degrees below Mobil 1 if I recall. I was surprised how good the Aeroshell was in that respect. As a sidenote, I ran Aeroshell in the Sube for about 25 hours- and it didn't blow up.

Both oils have to withstand going through turbochargers where the bearing housing will be over 400F at the rear, towards the turbine end during operation and much higher than that on shutdown. I've never seen Mobil 1 coke on turbo bearings. It's awesome stuff at high temps.

[BillL]

Originally Posted by lr172

Gear tooth interface presents different wear factors than the cam/lifter interfaces. There is an insignificant amount of sliding or shear between the teeth. It's all pressure, not shear. With cam/lifter, it's both.

Could you explain that in a little more detail please.

[lr172]

Originally Posted by BillL

Could you explain that in a little more detail please.

In very simple terms, gear teeth roll against one another with the pressure point (essentially a tangent with a very small, effective contact patch) constantly moving on both teeth. The teeth don't slide against one another even though the pressure point (i.e. intersection of two distinct points on both teeth) is moving. The constantly moving pressure point creates a large wear patch, but it is not from sliding or shear forces. Clearly high pressure is involved (all force applied across a very small contact patch) and the oil must prevent wear. Different additives/properties are used for limiting the affects of shear and the affects of high pressure.

I am not a mechanical engineer.

Larry

[Bcone1381]

Originally Posted by jim etcheverry

Eaa has a nice video from Mike Bush well done on oil to explain everything about aviation oil.http://eaavideo.org/video.aspx?v=1149666747001. Long but great. You need to get to the TD sheet for the exact oil and look at the ash by wt.% and you'll find 1.2 to 1.6 for most of these oil. Mobil 15/50 http://pds.mobil.com/USA-English/Lub...l1_15W-50.aspx check out application ( Not for 2 cycle or aviation engines) also the ash content. You are right lead will be gone and even Mike Bush says when lead is gone it is time to look at synthetics. So this question in a valid question when lead is gone. Soon or Sooner.

Mike Busch's webinar is worth watching. You ought to watch it just to become familiar with who he is. A synopsis of recommendations from him backed up with truth and logic is based upon the fact that we rust out engines rather than wear out engines. 1) Use NO Synthetic oil. Revisit this when lead is removed form fuel. 2) Use Single Grade AD oil (50wt) 3) Use Phillips XC when sub freezing engine starts are expected. 4) Use ASL Cam Guard, but no other additives.

Lastly, Mike Busch's C-310 has run his two engines over 200% past TBO. 8 of 12 cylinders are original.

[bret]

Slight drift, just watched this vid, WOW! calling Allen from ASA, did you see this, this guy dose not like oil air separators.......I'm on the side of having one only because of the very poor, or lack of any baffling for the crank case ventilation path.