I've measured my oil consumption continuously since I bought the car in '84.. both before and since the engine was rebuilt.
Oil Consumption Spec's (from BBB) for the 230SL and 250SL are from 0.15 - 0.30 liters/100 km, or 0.16 - 0.32 qts / 62 miles.
Those spec's translate to 194 - 388 miles/qt. ...the higher rate of consumption (194 miles/qt) occurring at high speed freeway driving (according to the notation in the BBB).
For the last 5k miles before engine rebuild I averaged 292 miles/qt.... Cylinder #1 burning oil and fouling the plug badly. That was still better than spec's, but I didn't like adding a qt of oil every fill-up.... so it was time to rebuild the engine (117k original miles).
After the engine rebuild, for the 1st 5k miles I averaged 1258 miles/qt, with the consumption as low as 750 miles/qt with a period of high speed long duration driving. This was far, far better than spec's, so I assumed it was due to the tight engine.
However, for the last 5k miles, now with 14k miles on the rebuilt engine the oil consumption has averaged nearly 1000 miles/qt (991).... admittedly this is with high speed long duration and heavy on the throttle driving... while for the 1st 5k miles after the rebuild I drove more/less conservatively (by my standards).
I use 10W30 or 30W Pennzoil or Castrol.
I believe the much better rate of oil consumption experienced has far more to do with the changes in engine oil technology than to my engine's relatively new rebuild, since even with a bad oil compression ring on cylinder #1 and fouling the plug on it I was still getting better oil consumption than the spec's!
For reference to fuel milage (reflects how engine is used... therefore may also have a relationship to rate of oil consumption):
Spec's (BBB) are 14.6 - 23.4 mpg for average highway travel + 10% more for the automatic transmission.
At constant speed (110 km/hr = 68.2 mph) spec's are 22.9 mpg for the 230SL & 20.9 mpg for the 250SL... no adder for the automatic tranny.
I averaged 16.8 mpg before the engine rebuild, and 14.5 mpg for the 1st 4k miles after the rebuild.... even though I was driving "conservatively"... I assume this was due to the engine still being tight or that I needed a valve adjustment after the rebuild wear-in period or the combination of both.
For the last 5k miles since the engine was rebuilt I've also averaged 16.8 mpg as I did before the engine was rebuilt, so my guess is that mileage reflects how I drive my 250SL manual.... seeing as it's the same as it was before I had the engine rebuilt.
My best fuel mileage has been 19.4 mpg in liesurely cruising at 72 mph and my worst 13.1... the latter reflects a typical "First Sunday Drive" in the SantaCruz Mountains... hard on the throttle 98% of the time and in lower gears (2nd & 3rd much of the time).
Longtooth
67 250SL US #113-043-10-002163
The 6% Club - Best of the Best
'02 SL500 Sport