[tubman]

I don't give it one bit of credibility. Get all of the crap out of an old engine that you can. All detergent does is keep crap in suspension, so change the oil regularly. If it has that much sludge, it's a candidate for a rebuild anyway.

Pull the pan and the intake and clean it up and flush it with kerosene etc. if you really care about saving an engine. We've all seen the pictures of engines where the crud in the pan completely surrounds the oil pickup. Get rid of it first!