G'day

I have only run aircraft engines. Lots of them. My engines seem to last quite a long time. Several years is typical and the only engine I think I actually wore out was my first one - an OS 15 II way back about 1960. I ran it too lean most of the time and it wore very fast as a result.

As for tuning, most of my engines need very little tuning apart from when the temperature changes a lot in Autumn and Spring and when I change fuel mixture or prop. Mostly I fly the engines week after week at the same tune.

The tricks to getting engines to last is -

1. Don't tune too lean. Too rich is slightly less powerful but will last a lot longer.

2. Don't feed the engine a "high silica diet". ie Keep dirt out of the engine. Use a filter and clean it.

3. Keep the engine clean too.

4. Use as little nitro as you can. Nitro can cause rust from its combustion products. It does make tuning easier but it will shorten the engine's life the more you use. Up to 15% is usually OK.

5. Use enough oil in the mixture. I always use at least 20% of which one quarter is castor oil. Castor is a great insurance against lean runs and rust but it does cause varnishing and is gunky.

I had one Saito 45 four stroke that I and others ran for over 15 years. It needed some new bearings when it was about 15 years old but I believe it is still going and is now about 20 years old. They can last a long time.

Cheers

Mike in Oz