I added a 212 degree oil thermostat to my 502mpi last year. The dyno run found that the stock non thermostat system was only getting up to 140 degree oil temps. I see that there is a 180 ish oil thermostat available as well. Should i have gone with that, or stick with the 212?

Where is the dyno getting the water and what temp is the water? Also you arent holding the engine on the dyno long enough to get the oil warm enough like in a boat.

dyno was getting the water from an outside tank. Don't know the temps, but was prolly pretty cold. It was last week of september when it was dynoed. Either way, a 212 oil thermostat can't hurt.

Cloud,
The thermostat only opens when you reach the rated temp...212. You don't want it to open any sooner or you won't be able to cook off the moisture. If you stay at say 4000+ RPM's for a run, you will build some oil temp and the thermostat should hold the temp at the opening level indefinitely, assuming your oil cooler is large enough.

Yeah, i spoke with the engine builder today too about some other things and brought this up. He like the idea of the 212 vs 183 as well.

I have run the 212* Hardin Marine oil thermostat on a 600 hp 502. it worked great, oil warmed up quick and stayed between 200-220 almost all the time, kept the moisture out of the oil.