The manual just says to use "recommended engine oils". "Info available at your MB dealer".

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Jean

97 C280, 36k miles
96 Subaru Impreza Outback Sport, 146k miles

At the minimum you should be using oils that meet/exceed the MB spec for your vehicle... A C280 probably requires an SJ oil, I don't know if 100% synthetic was required then. As to weight, if it is cold you are worried about you can usually go with a 5W-x oil vs. a 10W-x oil, making sure you cover the higher number as required by the spec for your vehicle. MB's used to require both a gas and a diesel spec (i.e. SG & CF) for the gas engines. I just use 15W-40 Chevron Delo or Pennzoil LongLife.

That being said, the manufacturers almost always will agree that if you mix one weight of their SJ (or SL or SM) oils with another weight of their SJ oil there is no problem. Actually, almost any synthetic oil you buy will state it is compatible with any oil meeting the same API grade.

What you don't get is a new viscosity. 4 quarts of 10W-30 and 4 quarts of 20W-50 do not equal (or magically become) 8 quarts of 15W-40. You have 8 quarts of oil, 1/2 of which are 10W-30 molecules and the other half are 20W-50 molecules. This is not necessarilly a bad oil mix. Mixing brands adds the possibility of mixing different additive packages, which probably won't hurt your engine but may not result in the "ultimate" best mileage, performance, oil life, etc.

Just not really necessary. All the modern oils are really good, most are way better & some are totally outstanding. Delvac 15W-40 or 5W-40, Amsoil 10W-40 and 15W-40 would all probably work well for you. And there is an Esso 100% synthetic product that the Canadians on Bobistheoilguy.com just swear by!

Cheers!

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'91 420 SEL @ 199K, '92 SVX @ 181K, '93 SC400 @ 86K, '93 Kaw ZX-11 @ 30K, '87 F250 @ 181K , 2001 Valkyrie Interstate @ 6K, Y2K Honda NightHawk 250 with 1.5K, '88 420SEL I.@ 179K & the 2nd latest, an '88 420SEL II.@ 210K runnin' parts car, '85 F150 300/NP435

Hmm I'm used to my W126 it recomends about a 1/2 dozen different weights and the temps they can be used in. Just ask the dealer probably 0w-40.

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1999 SL500
1969 280SE
2023 Ram 1500
2007 Tiara 3200

why is Synthetic Oil so expensive... you can get regular oil on sale for a bit more than a dollar a quart. synthetic is 4x that.

Synthetic base stocks are more expensive because they are "synthesized" in a petrochemical process rather than being distilled out of crude oil.

Also, the profit margins are higher and the industry spendings millions per year trying to convince John Q. Public that synthetic oil is "better".

In reality, synthetic is really no better than conventional mineral based motor oils assuming you follow a traditional oil change schedule. Because synthetic base stocks are more resistant to oxidation, they have longer service life and are usually accompanied with an OE oil monitoring system, but using synthetic
in an older car and changing it at the normal interval recommended for a conventional oil is a waste of money, but without a monitoring system you don't really know how long you can go.

The most critical aspect of a motor oil is the ADDITIVE PACKAGE and all API SL oils have about the same additive package regardless of base stock. Since most of these additives
are consumed during service, synthetic oil with longer change intervals is certainly NOT an improvement.

The basic advanages of synthetic are longer service life due to due slower base stock oxidation rate and a wider viscosity range with little or any VI improver, which break down with use. That's it.

Duke

Turbine oils have been synthetics for many years. It sounds like piston engine aviation people are even more reluctant to change anything then MB people are.

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Norm in NJ
Next oil change at 230,000miles