I have had the SDL for about four months and am still learning all kinds of things about it. I recently changed its oil for the first time and put in Rotella synthetic, right up to the "do not exceed" line. I was quite careful in this process because I wanted to determine the oil consumption the next day when I took it on a 400 mile trip.

So, I finish the trip and check the level after letting it sit for 12 hours and find, to my chagrin, that the level is about 24 oz. less than when I started. Not a good sign.

I add no oil, hoping that it will burn less oil on the return 400 mile trip with the level closer to the "do not go below" line.

I check it after returning home and letting it sit for 12 hours. The level has now increased so that it is now down only about 6 oz. from the oil change.

Very interesting phenomenon. I have figured it out. Anybody want to hazard a guess? I will tell you in advance that it is not water or any other contaminant in the oil (to the best of my knowledge and belief).

I have had my 603 only a short while too and I have noticed from time to time that the readings were a bit screwy, not disimilar to your findings but with one exception, I leak oil out of the head gasket and I loose too much to know if it is burning it or not!

So, whats the secret? Does the oil in the filter, or oil cooler somehow find it's way back to the pan as the pan is lower to earth?

The secret is that the vehicle was parked in a driveway with a slight uphill incline after the first part of the trip. The dipstick on the 603 is right up at the front of the oil pan.

Mine does the same thing, sometimes it's about halfway, then the next time it's almost 3/4. I think maybe it has to do with how long you wait to check it. These engines form a vacum in the oil filter hoseing. Crack it somtime when the engines warm, all of the oil will drain down to the pan quickly.

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1999 SL500
1969 280SE
2023 Ram 1500
2007 Tiara 3200

When I change the oil in my SDL, I only put in 8 quarts, thus my dipstick reads about 7/8ths. The oil level remains constant with a very slow lowering as I approach the next 3000 mi change. (use approx. 3/4 quart in 3000 mi.) The SLIGHTEST incline will affect the oil level reading. I use this to my advantage when I change the oil, because I point the car (very slightly) down hill on my driveway, thus I can suck most, if not all the oil out. There are 2 ways that I can tell that I get the oil out. 1. The amount that I put in (8 qts) is always below the full line (7/8ths approx.). 2. The oil is so clean that it is hard to read for the first 100-200 miles. If I change the oil in the garage, where the floor looks level, but actually has a very slight up hill incline, I can't get quite all the oil out (8 qts fill it) AND the oil looks dark after a 5 min. run. I use Rotella T since it is known to be a good cleaning dino oil. ( I prefer to change dino oil more often to get the "soot" out, rather than use syn. oil and extend the oil change period. And, I don't have really cold temps to worry about, since the garage is heated.)

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Paul 1987 300 SDL; 2000 ML; '69 MGB; '68 VW Fastback

The proper fill amount for your OM603 engine (and all OM601/602/603 engines) was retroactively reduced by half a qt in 1991 (TSB 00/86a & 01/21). Total fill should not exceed 7.9 qt vs the 8.45 qt listed in the owners manual and shown at the MAX mark on the dipstick. Then there is the fact that many Mercedes engines tend to consume excess oil at highway speeds if filled to the MAX level. This is covered in TSB 00/57 warning owners to NOT add oil until the oil level drops below the ADD mark. They warn to NOT frequently top up to the MAX mark and that the optimum level is midway between the two marks.

Finally there is the problem that some synthetic oils drain back into the pan VERY slowly and that even many minutes or a few hours after engine shutdown the pan oil level as measured by the dipstick does NOT properly reflect the actual quantity of oil in the engine. Tbis is MUCH less of a problem - almost a non-problem - with conventional oils. When using a synthetic, if I add oil based on a reading take even many minutes after the engine is shut down, the next morning (after the engine has sat overnight) the level can be as much as a qt overfilled and this oil will usually be expelled from the engine rather quickly.

I have found that using the oil level measured shortly after the engine is shut down it is VERY diffricult to estimate the actual quantity of oil in the engine - at least for me (and I've tried for a good many years). I now measure oil level BEFORE the engine is started. When driving I will add no more than one qt of oil if the level measure a few minutes after the engine is shut down is well (5+ mm) below the ADD mark.

Mercedes has solved the problem - they have elimated the dipstick in their newest cars and the only indication that oil needs to be added is when the low oil level light illuminates (equivalent to the level dropping below ADD).

Marshall