I have a S60FT with the 2.4L GM engine that blows a puff of smoke on start-up. I am reasonably sure that the smoke is not from the rings or valve seals. Does not appear to be getting oil in through PCV system. No oil/coolant consumption complaint. Smoke smells a little like oil but also like old gas (this is an LPG only unit). Smoke is whitish. Anybody experience something like this??