I think I recall someone stating that they use Mobil One, but that is not a diesel-rated lubricant. I checked the level on my "new" 82 240D yesterday and it was more than 2 liters low and very dirty and topped it up. P/o left 7 new Mann (? green and yellow box) filters in the trunk. I quickly picked up a few gallons of Shell Rotellac 15w-40. It stated it was rated to conform to Mercedes spec 288.blabla. Drivers manual says nothing about grade CD or whatever. Better close than not at all.

So what kind of oil do you use? Anyone found a synthetic rated for diesel? I think Mobil makes a Delvac grade that is synthetic. If you use a synthetic or other extended-life oil, what change interval do you observe?

 

I use Shell Rotella T 15W 40. We used this oil for years in our school buses when I was a mechanic for the local school system. We ran International/Navastar 6.9L, 9.0L and DT 466 engines, 8V71 and 8.2L Detroit engines along with a John Deere backhoe and several 3600 Ford tractors. The oil held up fine and we never had any oil related failures. For a long time we would send off samples from each bus to have it analyzed but they never found anything outside nornal wear so we stopped wasting the schools money. My thoughts were; if it is good enough for those heavy duty engines it would be ok for my two Mercedes cars.

I hope this helps.

Tony T

 

I just switched from Mobil One 15-50 to.... Rotella T "Advanced Soot Control" Synthetic 5W-40 and paid $13.44 for a 4 quart jug from WalMart......

I change oil at 5K........beyond that, soot count starts to climb. ............BB

 

Woah, $14 for 4 quarts of full synthetic? Excellent price.

What does MB-branded motor oil cost (I assume that, like BMW, they are happy to sell you oil guaranteed not to void your warrantee and vastly inflated price). Two weeks ago I bought a couple of gallons of BMW antifreeze for my M5. Cost me $24.95 per gallon, up from $15/gallon a couple of years ago.

 

$25 a gallon for aluminum safe anti-freeze is what they are selling you! That's worse than the MB stealership! I paid $12 plus tax for a gallon of Mercedes version of the same thing. You can now buy aluminum safe anti-freeze from all auto parts stores for about $11 gal.

I thought MB, AMG, approves Mobil One for use in all it's cars!

 

I was at Wal-Mart today and found both the synthetic Rotella and Delvac. But I see the Rotella T synthetic is a 5w-40. Isn't that a rather low weight oil for an older engine design? Newer engines are designed for low-weight oils to save fuel. But older engines were not and an excessively low viscosity can lead to premature wear. Given the loads on diesel main bearings, I would be very wary of low viscosity oils. The Mobil 1 15w-50 is great for my BMWs precisely (M5 with S38-B2 and 2002 with old M10) because of the high viscosity.

 

the 'w' in oils isn't meant for weight but it means winter.
and as engine gets ol you should increase the 'w' number. to find out check the pressure of oil at different viscosity. if you put low viscosity oil on old engine it will lead to faster ware of engine because of pressure of oil will escape through main bering, but high viscosity oil wont be able to oil the main bering becouse it wont squize through the bering.
PS the 'w' number is for winter the lower the number for colder weather its meant for, next number is for summer the highest it can get. 15w-50 is for summer, or for very old engines (not by age but milles it got). 10w-40 or 10w-30 is best is for all wether. 5w-30 or 0w-30 is for very cold like canada whether, or for new or fully rebuild engines. The letters is meant for when engine was build like CF, CE for newwer engines and older, like SL, SG, SK. C for diesel, S for gasoline, I preffer oil that for both engines (divided by slash like SL / CF).
check by presure of oil on idle and hot engine you should get ~2, if 15w-50 gives you 3 try and use 10w-40. but if you get 2 or less on 15w-50 your main bering are gone you should do rebuild, or leave until engine dies.

 

Kakarot, I think you are rather pessimistic. MB marks their gages in bar, about 1 atmosphere. So 1 bar = (about) 14.7 psi, 2 bar = 29.4 psi, or almost 30. 30 psi at idle is plenty of oil pressure, remember that what's doing the lubrication is not the pressure of the oil but the hydrodynamic film that forms due to the motion of the crankshaft.

I should have recognized the point that 5w-40 is a 40 weight oil that is pourable it a temperature that a straight-weight oil would jell. I'm using Rotella 15w-40 for my first oil change, since what was in there was very dirty and I don't know how old. I'll change again after about 1000 miles. I'm just a bit reticent about using synthetic in an engine with this many miles (180k+ on a sometimes-working odo). I've seen synthetic trigger leaks in older engines. Twice. Both times it was the rear main seal and I think that the synthetic dissolves varnish that had been helping to seal an almost-gone seal.

Anyway, thanks for all the advice.

 

actually in any oil designation there is no 'weight'. The last number in designation means how much oil can pass through an opening when it is heat uped up to 100C. but you should think more about the first number. as engine becomes older you need to increase the number with 'w' due to lost in pressure. If you had your car for whery long time you whould notice that when car was yonger pressure was high, but now its low.
nonsence syn oil cannot do that. syn oil helps engine becose it doesn't burn as regular oil. If you have engine more that 125K miles use 10w-40 to 15w-50. if you have engine more that 200K miles use 15w-50 to 20w-50. if you have more that 250K miles 20w-50 to 25w-60. and so one