mmrando

2003 Dodge Ram 2500 4x4 5.9L Turbo, 332k Miles. Past 24 mths,: new injectors, fuel pump, fuel filter housing, fuel lines, and I'm sure a few other things. Past 9 mths: new transmission/torque converter, front end rebuilt last week, 2 new batteries. Shortly after last oil change less than a month ago (Rotella T w40 and 1 quart Marvals Mystery Oil) she starts blow oil out of crankcase vent hose. The truck runs flawlessly, No hard starts, rough idle not knocking; no loss of power at any point, no decrease in mpg, not the first hint of any form of smoke. A/c does not work. Did the oil cap compression test, perfectly normal. No smoke or pressure there. Oil is on drivers side and only blows when moving. Any ideas? I apologize if my first thread is here as well. I'm new at this and didn't see it so I thought I may have done something wrong.

Desert5600

Drain the oil with the Marvel Mystery Oil, change the filter and fill with Delo 15W40. NO MORE MMO. Let us know what happens.

mmrando

Ok, thanks. Will let you know.

mmrando

Since new we have use Rotella T w/NAPA GOLD filter and have only on occasions run a quart of Lucas Oil Treatment thru it. Why my son went with something different is beyond me. If in fact it is the MMO causing this, what do you suppose is happening and is there the chance of any internal damage?

Desert5600

MMO is somewhere in the vicinity of 7.5W or 10W, so its diluting the oil. It doesn't change viscosity with temperature as engine oil does. If he's running something like 5W40 with MMO, then he's compounding the problem and blowby is created. It all depends on how much MMO he's using.

I used to run a 5W40 full synthetic in my 12v with extended drain intervals backed up with oil analysis. The engine would throw oil vapor from the breather. When I changed to Delo 15W40 the oil blowby stopped. That's why I suggested that.

If he thinks he needs MMO in the engine to resolve an issue, then he has bigger problems that MMO won't resolve. The solvents will eventually burn off, but I would drain it, change the filter and try the Delo or a 15W40 oil.

mmrando

I think he was just doing it "because". As stated, the truck has no known issues and is running great. Thank you so much for your input. We will certainly give this a try and hope for the best. Will keep you posted.

mmrando

Took the truck to local Cummins shop. Jr overfilled on last oil change by a whole gallon plus the quart of MMO. Not to mention he didn't completely snug down the drain plug. The changed the oil then tested everything else to make sure there were no issued anywhere else and she passed with flying colors. Thanks for your input.