As an experiment I ran a Fox .25 with a Meehanite piston and an LA .65 bushing engine on the Wildcat full synthetic. There was no hint that the synthetic lube was not doing its job, in the long run, I don't know, but I suspect they'd be fine. I also ran an old SuperTigre .51 in which I had installed a new Frank Bowman ring, it ran fine. That's all I've run Saitos and an OS or two on for about 5 years.