ORIGINAL: loughbd
Marvel Mystery oil works just fine as does marvel airtool oil. I mix Mystery oil 50/50 with ATF. My bearings never rust. Of course you have to get the fuel residue out of the engine. That's what rusts everything. You can add oil to acid but now you have diluted acid.
Right on mate...........that's what I've been doing since i switched to 4 stroke Saitos for the past 6 years, never had to change bearings. But I also run off the fuel after the day's flying sessions, adding also the after-run oil. Some flyers question why I add after run oil after the day's flying is over. While their bearings ceases and rust, mine are still shining like brand new, the added maintenance only takes a couple of minutes. The performance is much better. My Saitos are the 120,100X2, 91 and 72x2.
Over the winter a general maintenace is performed. 100 percent ATF or Airtool oil for storage.
Charles.