RE: OS 1.08 Nitro engine
I agree with Chad and the other responders the 1.08 was a wonderful and reliable workhorse of an engine with no special fuel requirements.
Here is one on the left in one of our most successful aerotow planes that was built from plans by the young fellow in the photo. We have always used pretty much the same fuel as for everything else which consist mostly of 15% Nitro (because of our elevation) and including a small amount of castor in the mix.
I also have a Magnum copy of the OS 1.08 that is also a great runner (and I am not ordinarily a fan of Magnums) that I use in my carrier landing airplane and I tend to throw whatever old stuff (fuel) I always seem to be ending up with on buyouts.
John[8D]