Hi All,

I recently put a good used 292 out of a 66 c60 in my 66 c20. It ran great! When I changed the oil I added a half quart of Marvel Mystery Oil to help clear out the old sludge and give the lifters a good cleaning out.

On my first highway trip I was about an hour outside of town keeping a watchful eye on the oil pressure when the gauge went to zero. I shut it down and pulled over to find that the oil pan looked like it had black spaghetti coming out of it! The sludge apparently cleared itself out exposing small corrosion pits and thus relieving the motor of its oil.

I had the truck towed home ($$$) and plugged the holes and added oil to find a LOT of noise coming from the motor that only got worse. I ended up putting my spare 78 c20 292 in it (the oil pan looks great!) and the truck is running fine again.

Lesson learned: Inspect your oil pan very closely on used motors!!!

EWWWW

Thanks, I'll try to remember that.

Med duty trucks such as a 60 series are more likley to rust through the oil pan than a pick up. I don't know why but always thought by being higher they had more chance of get salt splashed on then. In govt. use a chevy oil pan is good for six to eight years on a salt truck. Even the new cat diesels in the Kodiaks only last five or six years. The first few holes can be welded on the truck with a wire welder then the pan has to be replaced. Never had to replace a pick up pan when traded at ten years.

I wouldn't put anything into the oil that has solvents in it and run the engine hard or at high rpm.
MM-Oil contains Benzene, Mineral spirits and Naptha.
Idling in the driveway or short trips around town may be alright.
I know MM-Oil recommends it on their label and many use it in their oil, but its rather a gasoline additive and valve lube.
Oil thinned with solvents cleans alright, but doesn't lube very well.
In some cases, the oil pump screen can get clogged with sludge that has not disolved all the way.

Diesel motor oil, like Rotella or Delo, has 50% more detergents and 100% more dispersants than gasoline motor oil and is a better way to clean an old engine. It works slower and milder and cleans well over the long run with more frequent filter and oil changes than normal.
I got Rotella in both my daily 235 and even the new 261, year round.

I guess I should clarify the oil situation. I ran generic 10w30 with a half quart of MM-oil for about 100 miles on short trips. I then changed the filter and ran Rotella 10W30 before my trip out of town. I decided to go with Rotella after doing research on this site and others. I thought the MM_oil helped break up the sludge to expose the rusty pits, but it sounds like based on Road Runner's input it was the Rotella. It was running great before the loss of oil. It was definitely the running out of oil that caused the roadside break down though!

It will be interesting to disassemble and inspect the motor sometime in the near future. Thanks again for the input!