Dazed and Confused
Join Date: May 2012
Location: Upstate New York
Re: Oil sludge
Additives will help get the sludge out of the upper portion of the engine, but it'll also cause it to collect in the filter and sump. If you use any additive, use as directed, more is not always better. If you are heavily sludged, you'll probably want to pull the oil pan off and clean what collects there.
Take not, if you are that heavily sludged, it's probably best to at least pull the heads and sump and degrease it so that you're not using the flow of oil to clean the engine. If you run an additive and the fouling is loosened from the upper block, it has to flow with the oil through the engine to get to the sump, where, if it doesn't block a drain port, it'll be available to be sucked back into the system and through the filter.
Ever notice that there's so many high performance parts available for GM products?
Did you ever think that maybe they NEED them?