My 12V uses roughly a quart per 1000 miles. Only time I get blue smoke out the exhaus is at startup when it's cold out. I run Rotella Synthetic 5W40. How much oil consumption is normal? What could my problem be? Also, how long can I go between oil changes with the oil I'm using? Thanks for the help.

 

i have seen a lot of trucks that would be a half gallon to about a gallon low at every oil change. my old 24 valve leaked at the front seal, bout a gallon every 3000 miles. just find out where your oil is leaking, if it is. hope this helps you some what.

 

You might try a different syn oil or a 15-40. I use the same oil so I'm not downing the oil. Just sometimes the engine and your driving habits might be happier with another. You didn't say how many miles on the ol '94 and what kind of life she's lived. Do you have a oil trail from the draft tube? That would be sign of wear. Cummins has a test for measuring blowby and predicting engine wear level. Just might have provided to much entertainment for you.

 

My Cummins has 158K on the clock. Just bought it a coupla months ago so it's past life is not really known. It hasn't really leaked any oil on my driveway so I'm thinking I'm prbly burning it? But then again I don't get hardly any blue smoke except a little on startup when it's pretty cold out. What's a draft tube?

 

The breather tube that sticks down slightly into underbody windstream. Left side of engine. If that tube extends too far it will suck oil out and lubricate the underside and rear bumper of unit.

 

Going over some old posts to find out if my 160K donor motor is bad. I'm new to diesels and to cummins. My truck has the same symptoms. Has no visible leaks, starts right up, has good power, and delivers consistant 20 mpg. If i drive it every day the blue smoke on start up is greatly reduced compared to the blue smoke it generates after setting for two weeks and being started. While nobody really answered your question, it seems the symptoms you describe are not uncommon. I'm somewhat reassured. I was only worried if these symptoms were uncommon.

 

Is your truck getting to operating temp?...Last winter I had a heck of a time getting my truck to the proper temp and it burn't alot of oil...In summer it was ok..

 

Being new to diesels and cummins, I have no frame of reference for proper warm up time. Compared to the 468 big block gasser that was in the 85 dually the diesel takes quite a bit longer to warm up. It does reach operating temp (approx midpoint on factory gauge) eventually. If nothing else it has been consistant since it was installed. My other curiosity is that if on a trip where I'm starting and driving daily the blue smoke at start up is nearly nonexistant, however I still use (absolutely not leak) about a half quart per 1000 miles. Given the donor engine was an early 89 and 20 years old I'm starting to think I would benefit from replacing the valve stem seals. My experience with gassers was that even with low mileage these seals would harden simply with time and heat cycling. Any thoughts on my valve seal theory?

 

The smoke you are experiencing won't likely be oil smoke. It is related to incomplete combustion and is what is usually referred to as white smoke when diagnosing fueling concerns.

Generally speaking, low fuel supply pressure, late injection timing, or inoperative preheaters are the main causes. It was a common concern on 12 valve engines in cold climates. The stock timing setting caused a lot of trucks to smoke and run rough when cold.

 

I re-read your post...My truck has been burning about a quart ever 1000 miles for the last 5 years...Same blue smoke at startup.Another fellow with a 96 is the same also,even after replacing with a rebuilt head.I don't think you should be to concerned about it...

 

Thanks to all for your feedback and help. Your reassurances have provided me with a sense of relief. My newness to the diesels and cummins have left me with a lot of questions about just what is "normal" operation. I know at 7MPG with the old BB, the 20MPG I get now is AWESOME !!! I'm absolutely sure I made the right choice with this conversion.