Originally Posted By: dave5358
Originally Posted By: Oldswagon
What is the general consensus about the best additive to help clean an older sludged engine? I am helping someone clean an older pushrod V8 with a carburetor that has a some sludge due to lack of use and a very slight lifter noise. Would Auto RX be a good choice? Or maybe something solvent based? Maybe just run a HDEO? Obviously being an old engine I wouldn't want to damage any seals either.
Why not try these steps. Put in a quality synthetic oil. M-1 is good, but most brands should work. Drive the car a few hundred (or thousand) miles. Then, when the engine is very hot, drain the oil. If you can angle the vehicle to get more drainage (e.g. lower the oil drain hole) that will help. Let it drain as long as anything comes out - 30 minutes or an hour or overnight.
You might repeat the above steps a second time.
If you are determined to try something more aggressive, you could add a quart of MMO to the oil. It is very thin - about like 10w oil. The thin nature of MMO might help cleaning, plus it has a high solvent content. Again, drive a few hundred (or thousand) miles, drain the oil when the engine is very hot.
Do the above steps first. The only other thing you might try is dropping the pan and cleaning the pan while off the engine. That's where most of the crud will end up - particularly after doing the above.
At that point, refill with a good quality synthetic oil, most of which are high detergent and will attract and hold crud in suspension. Any crud that remains in the engine should come out with subsequent oil changes.
For such a short interval I'd use something more powerful like Kreen. I don't think a good synthetic, or oil spiked with mmo will do a whole lot in such a short interval. Been there done that. But hey give it a shot and report back.
I'd add mmo about 1k miles before the oci, dump it. Then run mmo the full oci. Different strokes for different folks.