Office of Steam Forum for Model & Toy Steam Gas & Hot Air Engines

I think there is a catch twenty two with regard to bore finishes. I am mindful of my dad’s experience back in the sixties,  manually machining bearings for gas turbines. They were large diameter sleeves cut to +.0003/-0.0”, with mirror finishes.  They lived or died on the idea that the smoother you got a bore, the less surface oil film required.  By contrast, assembly line, pre-CNC car engines were iron bores of far sloppier tolerances, which used textured crosshatching to retain essential lube. I also remember a ‘59 Ford 289 that was huffing oil past the rings at under eighty thousand miles when dad got rid of it.  By contrast, stainless sleeved engines are a thousand times smoother, and require less oil because an oily fingerprint would be enough to protect them. A friend ran an 08 Toyota 145000 highway miles on the original factory oil.  It was exactly half a quart low when changed.  We beat the daylights out of that car, often hundreds of miles at a rip at 90-100 mph.  It never complained.