fd_neal

iTrader: (4)

[QUOTE=Barry Bordes;9035249]

fd_neal,
If you use viton orings on the oil control rings I think synthetic oil would be OK.

Barry
QUOTE]

Interesting, Im using mazda O-rings... Ill wipe what I can off and drown them in some regular 5w30, I figure I risk more damage getting them out and back in then with a small amount of synthetic that should get rinsed out once the motor is run.

rd_turbo

iTrader: (4)

The synthetic/mineral debate has gone on for years. The fact is that synthetic oils have evolved substantially over the last few decades. Rubber seal compounds respond differently to different types of oils. Rubber can either expand or shrink in oil, depending on the formulation. The reason synthetic oil is bad in rotary engine is due to the fact that oil is injected into the intake stream and ends up being burned. Over time, the build-up of dark, glass-like deposits on the seals and rotor faces can be substantial. An engine that is driven normally and loses compression at a normal pace as things wear out will respond poorly to synthetic oil. The deposits will do nothing but further compromise already weak seal springs. There is absolutely nothing wrong with running synthetic oil if the metering pump is eliminated in favor of a premix approach, or if a metering pump adapter is used which allow fresh 2 stroke oil to be ingested out of a remote reservoir as opposed to crankcase oil.

Back to your oil control rings. The fact that the entire control ring assemblies simply fell out is not alarming...it's normal to see that in a used engine. The inners tend to do that while the outers tend to stay put for the better part. If your measurement of .035 to .040" represents the wear area on the control rings, it's not surprising considering the damage to the irons. I've seen control rings that had a good .030-.040" ring and the engine was not smoking significantly. The trick is to make sure the springs are oriented properly and that the spring tangs are engaged with the dimple in the rotor and slot on the control rings as specified.