Mercedes Confused, Too (re: viscosity)
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JHZR2
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I'd assume that Daimler was worried about viscosity at the bearings at startup, or some other sort of issue pertaining to the quality of 5w-vs 10w-30 oils back in the day.
Daimler was the engineering group to trust when it came to automotive topics. Everything they (used to) do was based in thurough analysis.
With your OM617.952 in texas, Id simply put delo 400 or a decent 5w-40 and be happy. Use UOA to ensure that youre not loading up too much soot, and youll get a VERY long life...
You lucky dog - an 89k w126 diesel with an OM617????? I dont like you very much, Im super jealous
Daimler was the engineering group to trust when it came to automotive topics. Everything they (used to) do was based in thurough analysis.
With your OM617.952 in texas, Id simply put delo 400 or a decent 5w-40 and be happy. Use UOA to ensure that youre not loading up too much soot, and youll get a VERY long life...
You lucky dog - an 89k w126 diesel with an OM617????? I dont like you very much, Im super jealous
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The oil recommendation chart in the owner's manual for my 300SD shows 10W-30 good for -4 to 50F. It shows 5W-30 good for temps no higher that 14F
No wonder the general public is utterly confused...reading nonsense like that.
Tim
I am sure they are talking about 5W-30 dino oil. Maybe they left out that part or maybe you overlooked it.
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VW and Audi manuals also show an ambient temp limit of -10°C (14°) for 5W-30 multigrade oil -- IF IT'S MINERAL OIL of the lowest quality that still meets the MINIMUM requirements. There is no defined upper ambient temperature restriction on any synthetic oil.
The manual for my 1980 Pontiac Bonneville, which I had from 1980 to 1986, is somewhat similar in its oil recommendations. It recommends 5W20 from below -20 to +20. It recommends 5W30 only from -20 to +60. It recommends 10W30 and 10W40 from 0 to above 100. It also recommends straight 20 weight, 20W40, and 20W50 when the temperature is above 20, and straight 30 weight when the temperature is above 40. All temperatures are Fahrenheit.
It appears that a lot of manufacturers were not into the 5W20's and 5W30's of the early 80's. All these different viscosity recommendations were typical back before CAFE rules required that manufacturers only mention the viscosity they used when determining the fuel mileage of a given auto. Hence the spreading use of the 5W20 recommendation for many vehicles. It leads me to believe that it doesn't much matter what viscosity oil you use, except for small variations in fuel consumption.
It appears that a lot of manufacturers were not into the 5W20's and 5W30's of the early 80's. All these different viscosity recommendations were typical back before CAFE rules required that manufacturers only mention the viscosity they used when determining the fuel mileage of a given auto. Hence the spreading use of the 5W20 recommendation for many vehicles. It leads me to believe that it doesn't much matter what viscosity oil you use, except for small variations in fuel consumption.
The VI improvers were not very good back then. It's the reason GM issued a TSB in 1980 forbidding the use of 10w40 due to cam lobe scuffing that was so severe it resulted in engine failures. But with 5w30 the real culprit was Group I base oil. In the cut that would be necessary to blend a 5w30, volatility at operating temps over say 50F would be drastically high. This would result in excessive deposit formation and oxidation.
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Just mock me instead.
I'll buy the explanation that back then the Mercedes engineers didn't think much of the 5w-30 mineral oils.
Of course, it begs the question that with today's SM mineral 5w-30, would the Mercedes engineers still hold to this recommendation? I've read in Mercedes forums where drivers for these old cars have used everything from 5w-30 to 20w-50, with no lubrication problems noticed. I'd say most are using some kind of Xw-40.
I've never had any problems with the 15w-40, even in the winter around here.
I had a wheel bearing replaced on the old BMW last month, and the indie mechanic changed the oil for me, putting in Mobil conventional 10w-30. It has an oil recommendation suggesting Xw-30 oils are for winter temperatures. There's only about 700 miles on it. I do notice it revving a little quicker than with the 15w-40 weight oil, but maybe that is my imagination, who knows? Otherwise, no noticeable difference.
My gut tells me that you could probably use Xw-30 conventional oils and as long as you aren't seeing any consumption problems or are taking it to a track, you probably wouldn't have any oil lubrication issues.
Give the 5w-30 conventional a shot and tell us how it goes, I say. There are those of us out there who would be interested in the results. But hey, I'm enjoying reading G-Man's experiments with the straight 30--that's so old school is sounds new and original!
Of course, it begs the question that with today's SM mineral 5w-30, would the Mercedes engineers still hold to this recommendation? I've read in Mercedes forums where drivers for these old cars have used everything from 5w-30 to 20w-50, with no lubrication problems noticed. I'd say most are using some kind of Xw-40.
I've never had any problems with the 15w-40, even in the winter around here.
I had a wheel bearing replaced on the old BMW last month, and the indie mechanic changed the oil for me, putting in Mobil conventional 10w-30. It has an oil recommendation suggesting Xw-30 oils are for winter temperatures. There's only about 700 miles on it. I do notice it revving a little quicker than with the 15w-40 weight oil, but maybe that is my imagination, who knows? Otherwise, no noticeable difference.
My gut tells me that you could probably use Xw-30 conventional oils and as long as you aren't seeing any consumption problems or are taking it to a track, you probably wouldn't have any oil lubrication issues.
Give the 5w-30 conventional a shot and tell us how it goes, I say. There are those of us out there who would be interested in the results. But hey, I'm enjoying reading G-Man's experiments with the straight 30--that's so old school is sounds new and original!
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I bet there is at least one BITOGer with a late model Mercedes. Maybe he can check his car's manual.
Do not forget that Mercedes, VW, Audi etc are sold not only in developed nations, but also in developing and 3rd World countries where oil quality may be sub-standard.
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