- Apr 5, 2004
- Pensacola & Vero Beach FL
JAG: I will admit, up front, that I have done little homework on these engines, and don't know a whole lot about them. With this said, the soot thing seems counterintuitive. Why, if DI engines are able to control their mixtures to the n-th degree, including significantly stratified charges, would they be sootier than comparable port injected engines? If anything, I'd think they'd be cleaner???
Originally Posted By: JAG
Direct injected gas engines produce significant amounts of soot while port injected gas engines do not. Soot is abrasive so it increases wear and changing oil sooner reduces soot concentration. Direct injected gas engines also increase fuel dilution relative to port-injected ones because some of the liquid-phase gasoline hits the cylinder walls before vaporizing. So yes, for these engines, oil life is reduced. Relative to similar port-injected engines, shorter OCIs and/or better oils are needed if similar protection is the goal.