Sludge shouldn't affect engine performance, at least not directly. It is more likely the sludge is a byproduct of something else that affects performance. I have two cars that have add-on filters that use a roll of toilet paper. You wouldn't believe how well they clean sludge. One trick you might try is adding about a half quart of automatic transmission fluid to the oil, then change the oil after a couple of days.
Friday, January 28th, 2011 AT 6:25 AM