Dexron used as crankcase cleaner?!

Messages
21
Location
Oak Ridge, TN
My son just got a typical "little ol' lady" Nova he is bringing back to life ('78 6L 250 cc). This 27 year old car has only 83k miles and was driven only around town, 3 miles at a time, for all those years -- really. Anyway, the insides are pretty gunked up. He had removed the head and cleaned up as much as he can get to, but from the looks of the engine oil, only 500 miles after a change, there's no doubt what must still be in the engine and pan. I have heard that substituting a half qt. dexron for a half qt. oil at the next oil change is a good way to clean things up. Has anyone had the nerve to do this?? Something sounds wrong about that, but I cerainly would appreciate your comments. Thanks!
 
Messages
12,385
Location
Northern CA
A lot of us here are adverse to cleaning methods that cut a bunch of debris loose at once. For good reasons too, I think. If it's at all reasonable to do so, dropping the oil pan and cleaning it out then using a slow acting cleaner like the one that gets plugged the most here is probably the best way to go. How does it run? Did he actually remove the head, or just the valve cover?
 
Messages
22,337
Location
Apple Valley, California
40 years ago trans fluid did contain more detergents than oil and it was added to oil to help clean things up. Todays oils have more detergents than trans fluid does so adding trans fluid won't help clean anything. I've had good luck just running a good oil and changing it every 1000 miles to clean out the gunk. Others here swear by Auto Rx, Seafoam etc.
 
Messages
809
Location
Granville, Ohio
I did this once on the advice of a co-worker a long time ago. I used it on a '76 Mustang II that was pretty gunked up. I poured a quart of ATF in the crankcase, drove it about an hour then flushed it out and replaced the oil and filter. It ran fine afterwards. I sold the engine about a year later. The guy I sold it to said that he dropped the oilpan and found the inside spotless. I agree that there are probably better engine flushes on the market, but back then most of the engine flushes were primarily kerosene.
 
Messages
1,904
Location
Canada
What about using biodiesel, probably the quintessential ester-based cleaner? Anyone tried? Safe to do so with seals (even on a short-term 'flush' basis)?
 

JHZR2

Staff member
Messages
45,982
Location
New Jersey
ATF used to have higher detergent levels than motor oil. Plus its thinnmer than motor oil, so theoretically it gets around and into tight places better, maybe flows a little better/faster/harder, and did its job. I would suggest he reomove the valve cover and the oil pan to clean what he can find. Im sure the gaskets wouldnt mind a replacement. At that point, use a 15w-40 diesel grade oil, which has a LOT of detergent/dispersants, and start from there. Id suggest he find Auto-rx and lube control, and use them as directed. Id do the Lubecontrol flush first, maybe on the oil currently in there, before he drops the pan, then do the auto-rx, then the rinse, and then see how things are. At that point, Id just use a lubecontrol maintenance dose, and let real usage and the chemicals already there to their magic... JMH
 
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