I purchased a 1991 300e 2.6. It now has 110,000 miles on it. I am finding that uses 1 quart of oil every 1500 miles. This surprises me.

The compression test done when I purchased the car (@105,000 miles) showed compresion of 150 across the board. The mechanic said this was very good. There are no visible oil leaks and it does not look like oil is going into the coolant (ie the coolant is not turning milky).

Is this kind of oil consumption normal for this age of car, or does it indicate that I have a problem?

Bill

From everything I have heard, your consumption is normal. When you fill it up, do you fill to the max line? Many people on this forum, including myself, have cound that oil consumption drops if you only fill the crankcase to half way between the Max and Add lines on the dipstick. I can't explain it, but it has worked for me.

You may be getting close to needing valve guides/seals, which I understand many of the older m103 engines need around 100-150k miles. i don't know if MB had changed to the new guide/seal materials by 1991, but it is worth checking out.

According to what's been posted here by pros and at one other MB car site, the valve guides were updated in 4/89.
If your spark plugs are dry and you're not leaking noticable amounts of oil, I wouldn't be alarmed about 1 qt. every 1,500 miles.

Oil Use
 

I own a '88 260E with the same engine. It has 129,000 miles and uses about a quart every 1500 miles. I have checked the spark plugs and they are very clean. I have come to the conclusion that adding a quart or two of oil between changes, whether normal or not, is a lot cheaper than an overhaul.

1500 miles/quart is not real bad. Certainly not worth a valve job. The integrity of these engines is almost entirely in the head.

My advice, keep the engine full of oil until other ills or increased oil consumption require a valve job. The head on these engines comes off and goes back on very well and if you do a valve job with new guides, you will think it's a different engine in the car.

Good luck,

I had noticed a similar situation with mine a few years ago, and it was traced to a leak in the front engine cover(?? for lack of a better term). That belly pan under your car is great protection in case you drive over those concrete parking lot berms that would otherwise trash your oil pan, but it also may conceal all but the geyser-like leaks under your engine. This is supposedly a common source of oil leaks for this particular model.

Once I got mine replaced, the oil consumption was dramatically reduced!

G-Benz,
I don't really see how the protective covering under the engine protects the car from physical objects such as gutters, curbs, and the like. It's flexible and the pressure of any object will push through the plastic (before pushing the car up) causing damage.
I know because I once went out of a gas station too fast, cracking my oil pan. THe covering was fine, except for a small scratch.

You are probably right, David, since a true belly pan would be made of aluminum or steel. The scraping sound sure gets my attention though, and it prevented me from trashing the car too much when I inadvertently ran over a parking lot beam that I didn't know existed. But then again, maybe it wasn't high enough to do any real damage...

...still, it does hide small leaks that may go undetected if you're not the type to peek in the engine compartment now and them.

Very true...

MBenz (Steve) gave me all of the part numbers to order a steel carter cage undercarriage for the C-class... might be cheap insurance!