My 300SE (91) uses a lot of oil, especially under acceleration and high revs.
Some blue smoke comes from the exhaust if I accelerate, not at constant speed.
No visible smoke at startup. Valve stems and piston rings are replaced 30.00 miles ago.
Any suggestions?

I wonder if the guides and seals were replaced? How long ago (in years, not mileage).
The updated guides did not come out untill 901? or so.

__________________
Benzmac:
Donnie Drummonds
ASE CERTIFIED MASTER AUTO TECHNICIAN
MERCEDES SPECIALIST 11 YRS

According to information provided by one of the pros here a while back, the M103 motors got new guides in April of 1989.

Go to the SEARCH facility and key in BLUE SMOKE in the search field. The majority of responses from the pros point to worn guides or valve stem seals. The former is big bucks; the latter not as bad as the head does not have to come off. Stem seals are a diyer job if you have the correct valve spring compression tools and compressed air to hold the valves up on the compression stroke.

Aside from oil loss thru valve guides/stems, you may also be losing it through the valve cover gasket, top front cover, head gasket, oil pan gasket; rear main seal. The loss from these most recently mentioned areas may not be that noticeable, but collectively, add up to more than you might imagine.

These 103 motors are definitely not the most oil tight I've dealt with, especially after you're use to dealing with Asian cars that never use any oil at any mileage.

I do not understand the mileage indication you've provided, but irregardless of where the comma should fall, it would seem your cars cylinder head was serviced not that long ago in terms of mileage. I would be suspicious as Benzmac is about whether the work was done at all. Next I'd wonder about inactivity - drying out of the head.

My 2 cents.

__________________
Mike Murrell
1991 300-SEL - Model 126
M103 - SOHC
"Fräulein"

Thanks for the quick response.
I'm afraid that I was not clear on the car history.
It is a 1989 300SE, runs on LPG most of the time. Gas is more than 5$/gallon in the Netherlands!
I bought it in 1997 with 120K miles. In 1999, with 160K miles it started to use oil and I removed the head. The guides were very worn, and I had them replaced (+ valves and seats) at an engine repair shop. One of the chain guides appeared to be broken and I stripped the engine to replace it. The owner of the shop advised me to replace the rings with "Perfect circle" rings since the pistons were now easily accessible and there was some leakage. The cylinders seemed to be in good shape, the factory hone was still present. The engine runs fine for 30K after this overhaul, and the oil consumption was much less in the first 20K. But now it is going up, and especially with high revs (kickdown) and it starts to smoke (blue) under acceleration.
Since I have it the car has been used regularly and it properly serviced (by me). At the moment I drive only 12K a year, because of the terrible traffic congestion I ride mostly on my motorcycle (lane splitting is allowed here and you can park on the sidewalk).
That I'm worried about the oil consumption is not because of the cost, witch is minor compared to the rest (1600$ road tax etc.) but out of concern with pollution. Half burned oil is very unhealthy.
When it stops raining I will do a compression test and replace the valve seals.

Rob