Has anyone ever had a problem like with my 89 300se where the car does not use much oil in city driving, but take a trip of 500 miles or greater and it will consume about a quart and a half during the trip. I have had a valve job done and the problem got worse. I took the car back and they reworked the heads and it is back to where it was before the valve job was done and they say that everything is the way it should be. I suspect the rings are gummed up and the local dealer suggested switching to Mobile 1 synthetic 0w 40 oil. They stated that it would clean the rings up some and if they are just gummed up, would help with the oil consumption. Help? Scott

The Shop Should have Done a Leakdown Test (WARM) for a Proper Diagnosis....If They OVERLOOKED a defective ring the Valve Job Would Not have Cured the Oil Consumption !

I Have Tried Using ATF on Gummed Up Rings and Have Seen Good Results With Using a Quart of ATF at the Next Oil change Then Dump it it 500/800 miles
Then Try The Mobil One

How many Miles on Your car?

Is The Car Using a Quart in 500 Miles?

The car now has 185k on it. It seems to only use about a quart and a half on a 700-800 mile trip where you have been driving at high speeds consistantly. Around town, it probably doesn't use that much over a 2000-2500 mile range. It seems the higher speeds causes the higher consumption.

I agree that the higher RPM's from the highway drive is making the oil consumption worse. My 90 300SE uses about a quart of reg. oil every 1000 mile of driving 75-80 MPH tach at 4,000. I use the new 0-40 and 15-50 Mobil 1 syn. and oil consumption has gone down to about a quart every 1400 miles. The valve seals were replaced at about 110K and oil consumption with the new seals was about 1 qrt reg oil every 2000 miles. I didn't think that was right so the dealer did a leak down test and found 2 cyl. to have a higher leak rate then normal but not bad enough to worry.
Why did you have your head rebuilt?
Dan

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In questioning the mb mechanic for solutions, he stated many of the older cars with the mileage mine had, needed a valve job to correct the problem. In doing the valve job, they reworked the heads(mechine shop). Has anyone heard of the Lucas brand additive? I have heard this is really good stuff for older cars.

I belive a quart a thousand especialy at high speed is well within factory specs at two bucks a quart thats a hundred bucks every fifty thousand miles..........
William Rogers........

No one has mentioned valve seals here. The M103 engine in its early form (circa '86) was known for poor valve seals. Doing a valve job without replacing valve seals on this engine would be like washing your feet and then putting on dirty socks.

A good place to start, as mentioned earlier would be a leakdown test.

Good luck,

Thanks for the advise. The valve job that was done was a complete valve seals and stems. In fact, it technically has be done 2 times due to the reworking of the valve job when I returned with a worsened problem. I am sure the mechanic did a leak down test. On the first valve job, excessive oil was getting into 2,3, and 4 cylinders and completely fouling the number 2 out causing a miss. It was redone and that helped the problem since the car has not starting missing and it has been a couple of months and before within 2 days it was missing. The machine shop stated they could not find anything wrong with the heads, but the amount of consumption was lowered when they reworked the heads the 2nd time. I have oftened wondered if the mechine shop really knew what they were doing. If I had the money, I would take to the dealer and have them replace the rings and do another complete valve job. But, unfortunately, I do not have an extra $1200-$1400. The valve job done by my mechanic cost almost $800. He said he had done probably 12-15 300se's just recently using the machine shop and this was the first one that had ever had any problems.

my 90 300te 4matic was an oil consuming pig.several things i did helped greatly.change the valve cover gasket .the head has a half moon shaped divet at the back where the gasket fits and this spot was leaking.change the oil filler cap gasket.change to a heavier oil.im currently using 20w50.the 103 engine runs hot and seems to just vapourize the oil.then it gets sucked thru the pvc bypass into your air intake.have a look at the inside of the hose you will see what i mean.all of these things together reduced oil consumption by at least 50%.on a recent trip down east i used only 4.5l for 5000km.speed averaged at 100kmph +.i am planning to do the valve seals sometime.just buying some time with simple solutions.

Scott, I too am experiencing the exact thing. Car only has 69k miles on it though. Mark

I have a feeling that it is sort of the nature of the beast because it seems like most all 6 cylinders have the same problem. I also have a 420sel with the v8 and it does not use a drop(knock on wood). It also seems to be that the 6's do not have quite enough power to pull that heavy of a car. I did, under ok from my MB mechanic, use the Lucas oil stabilizer and it seems like the initial starts are a little rough, but the acceleration from a stop light seems to be much better and smoother. It used to almost have to go into high(passing) gear to pick up decent speed from a stop light. Now, you don't have to kick it as hard. But, it seems like the oil consumption is still just about as much as it was before the Lucas. So, I don't know. My MB mechanic is puzzled by this.

I have a '88 260e with about 130k miles on it that was using about a quart of oil every 1000 miles. I replaced the valve stem seals and conusmption is reduced to about a quart every 1500 miles - not too bad.

I did a little research and read that modern engines are more efficient at regulating fuel and temperature so the oil does not get diluted with water vapor and fuel like it did in older cars. The oil level would actually rise in some cars due to liquids getting into the oil. The other issue, especially with mercedes, is that the engines run at much higher rpm's. Some oil is left on the cylinder walls with each stroke of the piston so it makes sense more oil will be consumed with the faster running engines.

All this aside, I bought a ''92 300e that really used a lot of oil, about a quart every 500 miles. I put new valve stem seals on, same as my 260e, and it uses essentially no oil between 3000 mile changes now. New valve stem seals were the cure for this car.

1 quart of oil for 1000 miles is expected. The owner's handbook should say that.

I was using about a qt. every 1000 and replaced valve stem seals + head gasket. That latter had started to leak just before the repair.

I'm now using < .5 qts. every 2000.

Some consider a qt. every 1000 miles in a 103 motor normal.

Having been thru this, I believe otherwise.