Come on now, y'all. Let's share good info from what we've learned. In the past couple months for sure there have been some good discussions from JAG, SonOfJoe, and MolaKule has chimed in too from what I remember on this topic. There are only two ways to really "flush" an engine/clean out accumulated crud. One is to use some kind of solvent (i.e. Kreen or Kerosene), or to use an extremely polar oil (i.e. Valvoline Restore) that is specifically designed to chemically remove carbon and deposits because it attracts the bad stuff back into suspension more strongly than the internal surfaces of the engine does so it can then be caught by the filter. This type of oil is generally significantly more expensive than regular motor oils, and was specifically designed by Cummins & Valvoline because even $72/gallon oil is cheaper than re-ringing or rebuilding a diesel engine.
It's been discussed over and over by some of the tribologists (SonOfJoe for sure) on this awesome board that the detergents in a normal oil do not work like the detergents you dump in your washing machine, so they DO NOT perform some magical scrubbing of your engine's innards like some others like to claim. HDEOs, PYB, etc. can only perform the function of stirring up some of the accumulated particulates on the surface to be captured by the oil filter; it will not de-varnish, nor de-sludge, nor work miracles on an engine that has been neglected for a long period of time. It has also been pointed out (I believe by Shannow) that Group I/II oils are typically much more polar than synthetic oils (Group III+) and that there was a marked increase in deposits in his turbines when the oils used switched from the lower group oils to more heavily refined, less polar oils.
Now, to return to value-added questions, OP, why do you think you need to flush your engine? Has removal of the valvecover or oil pan revealed particulate deposits? Or is there just some varnish through the oil fill hole that you wish to remove? If it is the former, you may need to pursue one of the solutions in the first paragraph. Trav had a great thread on Kreen that should answer any of your questions about it. If it is just varnish, generally there is no detriment to some light surface varnish, so save your money and just change your oil at sensible intervals. HTH!
It's been discussed over and over by some of the tribologists (SonOfJoe for sure) on this awesome board that the detergents in a normal oil do not work like the detergents you dump in your washing machine, so they DO NOT perform some magical scrubbing of your engine's innards like some others like to claim. HDEOs, PYB, etc. can only perform the function of stirring up some of the accumulated particulates on the surface to be captured by the oil filter; it will not de-varnish, nor de-sludge, nor work miracles on an engine that has been neglected for a long period of time. It has also been pointed out (I believe by Shannow) that Group I/II oils are typically much more polar than synthetic oils (Group III+) and that there was a marked increase in deposits in his turbines when the oils used switched from the lower group oils to more heavily refined, less polar oils.
Now, to return to value-added questions, OP, why do you think you need to flush your engine? Has removal of the valvecover or oil pan revealed particulate deposits? Or is there just some varnish through the oil fill hole that you wish to remove? If it is the former, you may need to pursue one of the solutions in the first paragraph. Trav had a great thread on Kreen that should answer any of your questions about it. If it is just varnish, generally there is no detriment to some light surface varnish, so save your money and just change your oil at sensible intervals. HTH!
