Tried this in lube forum, Didn't really get any attention. My 460 I believe has sludge. I've heard put a little ATF and it will eat it up, Same with kerosene, auto-rx, MMO, even seafoam. Even as far as using some diesel oil. But what is something that will eat this up and not take months to do it? I've never had a sludged engine so not sure what to do. I do currently have some MMO in it with what was fresh 10w-30 and it is already turning black but my pressure likes to change and doesn't stay consistent. RPMs have no influence on it. The oil I drained was not thick but was straight black and was somewhat cloudy. But not chunks that I could see. I need something that is proven to work, work well and not take 24 oil changes and a year to do it. An engine pull and physical removal is impossible at this time. Lets keep one more 460 alive, Lol.

 

I've heard of people using kerosene and diesel for de-sludging an engine, but I have never tried that myself so, I'm not sure how well that works or how much of either would be required to get the job done.

Synthetic oils have an inherent cleaning characteristic about them that de-sludges and engine however, they can also help you discover oil leaks you didn't know you had if the engine isn't sealed up tight enough...

From the sounds of it, you're not certain your engine is sludged. If it isn't, there won't be any "chunks" coming out of it. If there is sludge, and a cleaning agent is breaking it up, I would think that you probably won't see "chunks" as it's being incorporated into the rest of the fluid.

 

She has conventional 10w-30 now and does leak oil. I did not see any "chunks" when I drained the old oil but from the history I've heard on this truck and how she runs and how the oil looked, I have no doubt there is sludge. And if there isn't, I'd be very surprised. This engine is going to need some treatments ran through her to re-condition seals and rings. Maybe clear a tick under the valve cover. However, The old oil had the viscosity of water. Could I of gotten lucky and it just thinned out instead?

 

To the "just use oil and oil only" crowd, I just use oil and oil only on a good engine. But I've purchased vehicles where the engine was severely neglected. Then you have to use an aftermarket product. MMO works but it takes awhile. One product that works much faster is Kreen. It works fast and you may want to change filters regularly. It's also hard to get, especially if you live in California. Once again, I'm not a believer in "snakeoil" products unless it is absolutely necessary.
If you have severe sludge, you still may have to do a teardown.

 

Why not just remove the valve cover and have a look inside, thats easy enough and will give you an idea whats lurking inside. On occasion I use a product called BG 109. It helps free up sticky rings and clean things up inside. I sell it to people who don't regularly change their oil. I was never sure how well it worked until the last time I used it and now I know it works.
I had a Saturn come in the shop low on oil, like it might have had 1/2 quart in it. usually if you just fill it it shuts up but this thing still was knocking, almost like a spun bearing. I put the BG 109 in with some clean oil and let it idle. After about 10 minutes it was still knocking, 2 minutes latter it seemed to quiet down a bit, and a few minutes later it was completely silent, sounded like a new engine. I drained it out, new filter and new oil, and added the MOA that comes in the 109 kit. Now if the guy would check his oil once in awhile he'd be ok. You can find that stuff at repair shops and dealers. Also you can find it on ebay. BG Products, Inc.

 

aw hades i'll just send ya some of my wife's homemade soup ..... i've used it too polish the aluminum rims and tanks on some of my trucks , so imagine a little engine sludge don't stand a chance ...........

 

Seafoam works well, as does diesel fuel. Your filter will plug quick and the screen on the pump pickup may plug also, so a slow cleaning may be a better way to go. You're in an interesting spot with that engine, though, since with that flat tappet cam you need a zinc additive but that and the oils that have zinc and good cleaning cost a bit. The best engine cleaning oil I have used is Castrol GTX, but it's expensive and doesn't have zinc so that's another $10-$12 per change for ZDDPlus. Wal-Mart Supertech 15w40 diesel oil has zinc, and is cheap but doesn't clean that much. Maybe replace half a quart with ATF or Marvel, and just change the oil at 1500-2000 miles.
I know you want it done quickly, but that may not be the best way to go.

 

regular oil change minus 2 quarts, top off with diesel fuel and take it for a drive. not city driving just nice 40-50 mph country drive for an hour. dump it and fill with a good synthetic.