[chevytruckguy70]

Thats a question that has been asked ever since the engine was invented and you will probably get a hundred different opinions on the subject. In my humble opinion and experience from a few attempts at what you are asking I'd have to say do not in any way try to "flush out" the engine with any cleaner of any sort.

The reason being is that as your engine heated up and cooled down the used oil would leave deposits on all the surfaces which over time harden up and start to close oil ports. Just like cholesterol in your veins. And just for the same reason DRs do not scrape or run cleaners through your veins to loosen the cholesterol I would not scrape or run cleaners through your engine. Yes there may be a slow down of oil running through your engine now, but cleaners will cause this hard deposits to slowly loosen up (well after you have put you engine back together) and the pieces that come off will end up blocking off all oil flow in cam or crank bearings and lifters or even clog your oil pump screen.

My experience with this is that if you are not fully tearing the engine apart and cleaning everything then only clean the gasket surfaces and put it back together.