In actual engine tests both batchs of cheap vegi oil ran well and mixed well but there was increased mechanical noise from the motor indicateing a lack of viscosity at running temps/conditions, wereas the modified olive oil the improved running/starting qualities were still obtained but the mechanical noise had disappered -(engine sounded the same as if running on castor)

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Hi Stewart,
That is exactly what I found when using modified cheap cooking oil. After some time running an etherless mix with this lubricant I lost the wrist pin bearing in a PAW 09 []

After reading your original post about modified olive oil I gave it a try.... it does indeed run much quieter, similar to when using castor oil.

Andy,
I have tried a number of mixes, some etherless and some with different amounts of ether.
Non-ether and modded olive oil work well.
Non-ether and mineral oil work well.

10% ether and mineral oil with 8% castor.... ran well, good throttling, idled satisfactorily.
10% ether and modded olive oil with 8% castor... ran well, idled superbly and very slowly but hesitated slightly when the throttle was rammed open.

Mixing mineral oil, modded olive and castor..... superb slow idle, instant response to throttle. After 4 minutes at a very slow idle the throttle could be rammed fully open and the engine would respond without any hesitation. I don't think the castor oil was contributing anything to this, apart from some protection, it is only in there because I was diluting down commercial fuel which contained castor as the lubricant.

The mineral oil used was.... part synthetic oil produced specifically for diesel car use. My own diesel engined car uses it and it has various additives in it.

Testing of fuel mixes was done over a period of time. Some tests were 2 hours at a time. The engines were frequently refuelled as soon as they stopped and started straight away. I will be using the 10% ether mix with castor/olive and mineral oil lubrication for flying this season.
I hope to get a lot of hours in to see how well the engines stand up to this mix.

I could just as easily make it a non-ether mix, using a mixture of olive oil and mineral oil for lubrication. I think I will stick with 1 step at a time and use the 10% ether mix extensively before moving onto the next stage.

I have been flying a 15% ether and 25% castor mix. This has worked well without any problems, once I use up the small amount left I will then use the 10% ether and mixed lube fuel mix. If I go one stage at a time and prove it over a lengthy period then I can try the next stage and slowly build up some knowledge about the different fuel mixes..... that's the theory anyway...

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