Quote Originally Posted by crazy_boy View Post
dvldoc, speaking of sludge, is it safe to assume that sludge is from use of low quality oil + low quality filter?
Folks we have our self a winner, You got it crazy boy, it's the number on reason for sludge, second is other contaminates like coolant. Some engines are just sluge monsters due to a bad design, Toyota's 1997 to 2002 for example.

If you use a low detergent automotive oil then you can expect to have a sludgy engine. If you have a coolant system leak expect the same. That's why it's always best to know what's in your oil, It's good to pull your valve cover from time to time just to check if everthing's good to go.