I apologize for yet another novel-length post. I understand this aggravates people. But I feel like it's useless to ask for people's time unless you thoroughly explain the situation to the best of your ability. If I shortened it, details would be lost that might be the subtle nuances needed to solve the problem.

Last week, we finally put license and insurance on the '82 300SD so it's road-test legal now. When I bought it (purchased from family friends, and worth what I paid for it in spite of these problems, so there's no need to go into the "did the seller tell you", etc part of it) -- they told me (and I think genuinely believed) that it only really needed 1 quart of oil in between changes.

Well.

I drove it to Boone and back yesterday (100 miles each way), making the trip I needed to make and testing the car simultaneously. Had a cloud of smoke following me most of the way which must have been oil. It was honestly hard to tell WHAT color it was (oil = blue, diesel = black, coolant = white as far as I know) but it seemed to be blueish/black. In hindsight, it MUST have been oil. So this trip was 100 miles one way. When I got there, I checked the oil. Before I left the house (checked immediately before I departed) it was just a millimeter or two (trivial over-fill; let's please save the foaming-oil-runaway-catastrophe debate for another thread unless it's REALLY part of my problem) above the full notch on the dipstick. After 100 miles, it was down to about a millimeter above the very BOTTOM of the stick. That's right... not above the low notch. Above the bottom end of the dipstick.

Never lost pressure and no funny noises, but... that could have been BAD. I never ran it dry, fortunately.

It took 3 quarts to bring it back up to a level in between the notches. Probably 7/8 of the way to the top notch.

Drove it home. Another 100 miles. Down to the very bottom of the stick again but maybe not QUITE as low as the last time. I should mention that the first 100 miles included an 8% grade for about 2-3 miles, which was the time at which it smoked the most intensely (Cloud was lingering behind me on every curve) and the engine worked the hardest. It makes sense that the return trip, which was nice and easy and mostly downhill, used SLIGHTLY less oil because the engine wasn't really working as hard.

The engine has 160,000 miles on it. Here's the clincher. I have a receipt in the glove box for a "300SD Turbo" -- as in replacing the turbo -- from 02/10/2010. 8 months ago, the turbo was replaced. I do not know if it was new or used, and I do not know what went wrong with the original turbo. I am going to get answers to both of those questions later today hopefully. However, the part was $300.00 if that helps. If somebody knows that a new one would cost $700 or something, then that proves it's likely a used replacement. I'm going to ask him as soon as I post this.

So... I'm really lost as to where it could be going. My understanding is that there are (not counting leaks) 3 ways to BURN, not leak, oil through an engine.

1) Worn piston rings
2) Worn valve stem seals
3) Failed turbo bearing seals letting oil blow through the intake.

1. Piston rings... is it POSSIBLE for an engine with only 160,000 (known true) miles to have worn out rings? I know a gas engine would be worn out by then, but I thought the whole reason so many of us are at 200,300k was that these didn't wear THAT quickly. What test would I perform to determine if this is a problem? I will have an opportunity to do a compression test around Thanksgiving. Probably illuminating either way.

2. Stem seals... they couldn't possibly burn 3 quarts in 100 miles over 2 hours, could they? To say nothing of more like 5 quarts in 200 miles taking the round trip into account.

I don't really see the kind of smoke on cold start that you would expect from valve stem seals letting oil leak down into the cylinders overnight. In fact, it only really demonstrates oil smoke when you're under acceleration or interstate speed. The rest of the time it just has the little bit of smoke that a diesel always has. The harder the engine runs, the more it smokes.

Finally -- the air cleaner center was very oily when I looked in there after I got home. I took the cap off the filter and the center section (the hub around which the filter sits) was black and wet. That must be where SOME of it is going.

So... the first question is -- what is the likely cause of this EXTREME oil burning? If it's the turbo, what tests or observations can I make (without dismantling the entire exhaust and turbo to remove it from the car) to see if removal is warranted?

And incidentally -- my 1986 300SDL has a BLACK oil dipstick finger handle. The 1982 240D has a RED one, and the 1982 300SD has a WHITE one. Are these all correct dipsticks for the engines? I can imagine a previous owner replacing it wrong or something. I wouldn't want to be measuring with the wrong instrument when the problem is this severe.

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~Michael S.~
Past cars:

1986 300SDL
1987 300SDL
1982 240D
1982 300SD


Current:

1987 300SDL