You wished for new threads so I will have a go!
Aero engine oil for piston engines is quite obviously made, to put it simply, to cope with the huge temperature changes and low revving engines with high stresses. That being said what makes it different to any other engine oil and would a simple air cooled lawnmower engine be fine using it? If not why not?
The aero oils, Shell and Total, we use in our O200 are VERY cheap (and simple?) compared to the stuff I buy for my car – once the car engine is worn enough to need a top-up between services.
Yes, I’m sure that any air-cooled 4-stroke petrol engine will run as well on aero engine oil as they do on no-name motor oil from Aldi.
The only substantial difference is that many of us run our airplanes on leaded gasoline, so we are advised to discard the oil every 50 hours (equivalent to 2,000 miles for the average family car). At 50 hours the lead content of our used aero engine oil is typically about 0.4% but viscosity well within limits.
It’s an interesting question.
A really curious thing is that “high-performance” car oil (say Mobil 1) is about 2x the price of the more pricey aviation oils if bought per litre. In bigger quantities it seems to be in a similar ballpark, though I don’t buy either in “trade” quantities. It doesn’t appear to be obviously a lot cheaper. Car dealers tend to buy oil in large drums and the ones I have seen use no-name stuff.
Jacko is probably right because, among aviation oils, very little data is available showing one oil is better than any other provided the engine is operated regularly. With less regular use there seem to be differences, especially with the Camguard additive. Camguard also makes a big difference in the wear rates of some metals, regardless of engine operation – I found this in oil analysis and the Camguard inventor (@ed2) confirmed this is as expected.
However I am not sure how much life is left in my aviation oil after 50hrs, given some numbers I have. OTOH it could be that the oil is still working fine, but merely gets consumed faster.
Peter wrote:
A really curious thing is that “high-performance” car oil (say Mobil 1) is about 2x the price of the more pricey aviation oils if bought per litre
I’ve noticed that car and motorcycle oil is very expensive in Europe. In the US the Mobil 1 I use for my cars is about $5 US/quart, slightly less than Aeroshell, and cheaper car oil is about $2.50 US/quart. I’ve always assumed the high car oil prices in Europe resulted from some sort of tax intended to discourage you from changing the oil in your car frequently.
I naively thought (still think?) my car oil was more complex,to last longer, in a more accurately machined and controlled engine.
Thread drift: local grapevine says local suspicious guy had guarentee repair on his very low mileage, new, BMW refused as it was run on heating oil.
Would the use of car oil render the aircraft unairworthy and, if so, exactly why?
Would anyone know?
I have certainly heard of people who have run Lycoming engines on supermarket unleaded and supermarket car engine oil for many hundreds in fact more like thousands of hours and without any problems.
We run our O200 on Tesco Unleaded, as it’s the cheapest, but I buy Esso for my Astra. Why pay the extra for Supermarket oil when Aeroshell and Total are cheaper?
I’ve learnt that the A/C oil has less additives then other engine oils due to the fact that some of those additives or dopes found in other oil can cause sparkplug fouling. Never had a problem with that in any of my cars tho, and I usually run 30.000 kms or more on synthetic oil between changes.
