If you want a true internal engine cleaner do a search for a product called Auto-RX. I swear by this stuff and I have used it many times for my vehicles and customers.
My latest success story with it was a co-worker of mine whose wife has a Lexus car. It developed a rear main seal leak. He took it to Lexus for an estimate and they were going to charge him in the area of $1500 to replace the rear main seal.
So I told him that if the seal was not torn and was just leaking due to build up then to try a bottle of Auto-RX and see what it would do. So he bought a bottle from me. He said that at the time he poured in the bottle the leak would drip an oil spot on his driveway about the size of two half dollar coins.
Not a week later he came to me and said the leak had stopped and it has not returned since. It is by far, in my opinion, the best product out there for restoring an engine internally. It works in engines, power steering systems, transmissions, differentials, etc. I have seen it have DRAMATIC results on varnish and sludge build up. It is worth EVERY penny it costs and I usually keep three or so bottles on hand or more if I can for myself and customers.
