My zetec has 89k on it. From time to time, it has a knock on start for 3 seconds tops. It sounds pretty bad sometimes, bad enough for people to look at it like wow, that wasn't good...
It does it at random, I'm using the motorcraft oil filter thinking it has something to do with the check valve in the cheapers ones. But still will do it. I'm running 5w-20 I think, motorcraft synblend. But even with 5w-30 it does it sometimes.
Really I want to ask, is this something to really worry about. Or normal. My sisters 3.8 mustang does it sometimes. And a contour with a durtec I just picked up did it a couple of times...
