mwpayne

My 85 got about 138K on it, bet treatment has never ben done by previous owner(s). After reading this and other posts, seems some use MMO, others ATF. Seems to me that ATF might do a better job removing carbon after a 2 or 3 day soak.
More opinions please? I want to do whats best for the car.

Thanks!

yayarx7

there is a healthy debate on ATF vs MMO, I beleive it just comes down to personal choice. I have used both, but they were on motors that were bad so it didn't matter. MMO will prabably burn bleaner and smoke less. ATF might remove more deposits but I can't see it being that much of a a difference.

Just do one or the other.

82transam

iTrader: (18)

will both damage your cat?

DriveFast7

iTrader: (1)

ATF is also a very good cleaner, in addition to being a lubricant. I did the ATF treatment on a junkyard motor that had GOBS of carbon buildup, an the carbon literally came out the exhaust port in thin little sheets.

dunno if it'll damage the cat but cats are expensive, not worth the risk.

I'm suprised no one's brought this up before. What I did was I took the exhaust manifold off, did the ATF treatment, and let it sit for 2 days at a time (& did several treatments). When it was time to get the gunk out, I just put my 19mm socket on a socket wrench, popped it on the main pulley bolt and spun the motor several several times, ATF and carbon came right out the exhaust port. Cleaned up mess with Simple Green and H2O. When it came time to start it up I put the exhaust manifold back on and only a small puff of smoke came out the tailpipe. No moskito killing smoke screen for 15 minutes.

BradP

jimmyv13

ATF *supposedly* harms O2 sensors and cats. If you have neither then ATF it. If you have one or the other or both, use MMO to be safe. If you have cats or an O2 sensor, you could always unbolt the manifold as described above, that way most of the ATF will not go into the exhaust and possibly harm the cat or sensor.