oil detergents/internal engine cleaners

[sbrguy]

is there a product or addative that you can put into your oil for say a few hundered miles that acts as a detergent to break up or get rid of oil sludge or other junk in the enging so that when you do the next oil change all of this stuff comes out and the engine is essentially clean for the next oil change?

thanks.

[Hedgehog]

It's best not to use any additives or cleaners or anything except the proper weight oil for your engine.  Your oil already has the proper amount of detergent in it.  If you want to see how much sludge you have in your engine, pull a valve cover.  It's a strong bet that the inside of your valve cover is squeaky clean, with absolutely no sign of sludge.  In short, the ads you see on TV are just that, adverts to divert your money from a competitor or maybe from something actually useful to you, like carbon fiber.   

[Howie]

Any decent oil has all the detergent you need.  If you do have sludge just change your oil a little more often.