Berryman B-12 CHEMTOOL FUEL SYSTEM CLEANER (part #0116) has been used as a motor flush since the product was developed in 1958 and is still successfully used today. The caveat in doing so is that the composition of B-12 is so strong that it can break loose chucks of sludge in high-mileage and poorly maintained vehicles. These chunks can clog oil in the screen and starve the engine of oil. Berryman OIL CHANGE FLUSH (part #1216) does not use the same type of H.E.S.T. solvents found in B-12. Instead, 1216 is comprised of the same types of detergents and dispersants already found in motor oil for cleaning. While we still recommend checking the oil screen in high-mileage and poorly maintained vehicles, the potential for clogging with 1216 is greatly reduced.

This is about the best response I've ever received. Didn't hide anything. No weasel words. No lawyering-up. Provided terrific, specific information so that I can make an informed decision. I'm thrilled that I can continue to use B-12 before my every routine oil change. With oil changes stretching to 25,000 miles with some filters/ oil, a proper flushing is more critical than ever. A friend once pulled my Cherokee's oil pan and he said it was the cleanest engine he ever saw. That's B-12 Chemtool!

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I have been using B-12 for many years. I run it strait in my fuel injector cleaner set at the shop. It runs about 20-30 minutes on the 15oz. bottle when poured into the canister and hooked up to shop pressure! Anyhow I too have used it to clean the crankcase before oil changes on my own vehicles. I am happy to hear that its still safe to continue the practice, but I also agree that if you don't know the condition of the engine that it can, and will clog the oil pump screen if used for this purpose. I have seen one engine that was so bad, that just changing the oil caused it to blow up after being driven less than 25 miles. When torn down the engine was like chocolate pudding on the inside (with pictures to prove it). It's obvious that the previous owner never changed his oil, but just merely added to it when it got low.