ive got a 91 with 135,000 miles and it wasn't cared for at all. I have been driving the car for about a year and am about to do a full tune up. i was told that on an older motor that's probably full of carbon and sludge from old oil that i should add some marvel mystery oil. once i drive it for a couple of weeks it will break all the crap loose so it will come out with the old oil. any thoughts?

 

I read that MM oil is actually Singer sewing machine oil with high detergents.
Use it. It works. But you want to dissolve the sludge SLOWLY so chunks don't
make their way into places (hydraulic lifters) and cause problems.

 

Automatic transmission fluid (ATF) will work too.

X2 on slowly - plug the screen on your pickup & you're done.

 

^^^This^^^

Been doing it for many a year now. Works GREAT.

Next time your oil is low, add a quart. Keep your eye on the dipstick, like, check it once a day. It will get REAL black and thick, REAL quick; probably just acoupla hours of running. Change the oil IMMEDIATELY when that happens, substituting a quart of ATF for a quart of oil. Again, keep your eye on it, and keep changing it when it gets nasty. Depending on how bad it has got, and how burnt it is (that takes longer to soften and dissolve into the oil), it might take 3 or 4 changes before it's all flushed out.

Then in the future, acoupla days before an oil change, add a qt of it again, to keep it from building up again.

Another thing that works is diesel fuel, the same 1 qt principle; but that's a bit too ... violent ... for my taste.

 

Amsoil makes an engine flush to "prepare engine for synthetic". It's a little more aggressive than ATF. Basically the same detergents but concentrated. It's about $10.

I've had the best luck on sticky lifters with Rislone. ATF and MMO seemed to be less effective. Every time I've had a legitimate case of noisy, dirty lifters, Rislone has cured it in a short period.

ATF, MMO, and Rislone are all effective leave-in (short term, monitored) treatments, with my preference for the Rislone personally. The Amsoil engine flush is much more aggressive - you add it, idle the engine for 20 minutes, and then change oil and filter.

GD

 

thanks for the replies guys. I do have a slightly noisy lifter.

 

ATF definitely works.

 

Did this many years ago with a really good running 327, older woman wrecked car, low mileage 300hp motor. Really sludged up with primitive oil and seldom changed, city driving. Pretty much ruined the engine when all that stuff got loose and trashed up the lifters real good. I'd suggest running a good grade of standard oil and changing it every couple thousand miles. Over time it will clean out just fine.