Dave,

I hate to sound like a cheapskate although i am one nonetheless. I was wondering if you have any recommendations for a locally available after run oil as a viable alternative to ultra oil? I had thought of 50 weight aircraft (reciprocating) motor oil or exxon 2380 turbine oil as i believe they have little detergent properties and i can get some from work.

Thanks

IF you want to experiment, buy a new YS diaphragm, measure the OD with calipers and put it into some of your proposed oil. If the dimensions change, don't use that oil.
By the time you mess around with all that and spend a bunch of $ on parts to test, you could have bought enough UltraOil to last years!

Dave