engine oil

[phoenix]

From some brief research I have done, manufacturers of piston engines for aircraft suggest oil changes after 50 hours or 4 months, whichever comes first.

Aircraft engine oil is subject to a fair amount of contamination from water, due to condensation formed within the engine by altitude changes and the temperatures changes resulting to that - and as high the water content of oil can lead to surface rust and therefore potential pitting damage to surfaces of cylinder bores/rings and bearing surfaces, that is the main reason such frequent changes are mandated.

These recommendations are worth considering, I think.

[MGDavid]

Originally Posted by phoenix

From some brief research I have done, manufacturers of piston engines for aircraft suggest oil changes after 50 hours or 4 months, whichever comes first.

Aircraft engine oil is subject to a fair amount of contamination from water, due to condensation formed within the engine by altitude changes and the temperatures changes resulting to that - and as high the water content of oil can lead to surface rust and therefore potential pitting damage to surfaces of cylinder bores/rings and bearing surfaces, that is the main reason such frequent changes are mandated.

These recommendations are worth considering, I think.

thanks, I'll take it into account next time I'm racing at 50,000 feet

[RF_Racer]

Originally Posted by Al Weyman

Not if its tuned correctly surely and I did make reference to oil dilution if running over rich. I start my engine with no choke just a dab of throttle to activate the accellerator pump jets briefly. I then let it warm up before i drive it unlike a road car which is started and immediately driven with an enrichened mixture so which is worse? I would say the road car scenario.

Surely borewash would occur if you either have incorrect fueling or an injector thats too big in size.

[GORDON STREETER]

Most of the petrol will normally evaporate out of the oil when the engine reaches its running temperature.
Diesel fuels are worse for contaminating the oil as it just thins it out, and in severe cases will cause the engine to run with no control from the driver !
A change of oil normally brings the emissions down a fair bit so change it before you take your diesel road car for the MOT.
Just give a petrol car a dammed good thrashing on the day of the MOT !!!!

[Chris Y]

Originally Posted by phoenix

From some brief research I have done, manufacturers of piston engines for aircraft suggest oil changes after 50 hours or 4 months, whichever comes first.

Aircraft engine oil is subject to a fair amount of contamination from water, due to condensation formed within the engine by altitude changes and the temperatures changes resulting to that - and as high the water content of oil can lead to surface rust and therefore potential pitting damage to surfaces of cylinder bores/rings and bearing surfaces, that is the main reason such frequent changes are mandated.

It's my understanding that this is something that affects under-driven road cars too - condensation builds up, and if only short runs are done (to the shops, f.e.), then the engine never gets warm enough, and water can become a problem. However, in race cars, I'd expect the temp of the oil to boil off some or all of that moisture.

[Dave Brand]

Originally Posted by Chris Y

It's my understanding that this is something that affects under-driven road cars too - condensation builds up, and if only short runs are done (to the shops, f.e.), then the engine never gets warm enough, and water can become a problem.

Very common. It manifests itself as "mayonnaise" on the underside of the oil filler cap, causing a lot of people to panic & being assured by "experts" on Internet forums that their head gasket has failed!

[GORDON STREETER]

Originally Posted by Chris Y

It's my understanding that this is something that affects under-driven road cars too - condensation builds up, and if only short runs are done (to the shops, f.e.), then the engine never gets warm enough, and water can become a problem. .

Not only in the crankcase and cam cover but most of the engine parts.
Just find out how many exhaust systems are fitted to low mileage/slow driven cars every year in comparison to a rep doing a thousand miles a week !
Every gallon of petrol produces a lot of water (I can't be bothered to google it)
I have some customers that will do less than one or two thousand miles a year and when you say "it would be cheaper to hire a taxi" the normal answer is "I like my independence "
I wonder what I will say in a few years time

[Al Weyman]

Even if you changed it every 50 hours like the aircraft engine suggested above, the average race meeting is less than an hours running so that would give you 50 race meetings so change it once every 5 years

[dtype38]

Originally Posted by Chris Y

It's my understanding that this is something that affects under-driven road cars too - condensation builds up, and if only short runs are done (to the shops, f.e.), then the engine never gets warm enough, and water can become a problem. However, in race cars, I'd expect the temp of the oil to boil off some or all of that moisture.

This is particularly true of people who own old classic cars and like to roll them out of the garage on a sunday morning for a clean and to start them up "just to make sure they run ok". Trouble is, this is often on full choke and usually for only a couple of minutes. Done enough it only wash the bores because of the excess fuel, but it can end up with more water in the bottom end than oil!