What kind of oil to use in a diesel?
 

I just did my first oil change on a diesel, and had some interesting replies about what causes the oil to go black, and mine was watery. But some of the replies were interesting, talking about using a diesel specific oil. Prior to doing the oil change, I asked a MB parts place and one very respected MB shop, what kind of oil I should use. They both said the same thing, that if I'm going to change my oil every 3k, (so long as it's 15w40 or 20w50), it doesn't really matter.

I used Wal Mart's SuperTech or whatever it's called, the guy there said it's by ??(Mobile, was it??), but a respected company. There was only one oil he said people complain about it caking up on them, which was ?? (maybe Texaco?) I forget, but he said the SuperTech is good stuff.

What do you put in your diesel?

1991 300d 90k

Do a search. Lots of opinions (every one different) here.

Jeremy,

Does Walmart Super Tech oil have a C for compression ignition rating?

P E H

i use Mobil 1 fully synthetic in mine. I change it at 7000 miles (its rated to 10000) or sometimes i use their extended performance variety and change it at 10000 - its rated to 15000.

Use either Caltex Delo 400 or Mobil Delvac Super, either of these superb HDEO would suit you fine changed at 6000km or six months, whichever comes first, they both are rated CI-4+ and thats the highest rating for any diesel oil, for extreme conditions you can use the synthetic diesel oil Mobil Delvac-I but its quite costly and doesn't make sense for everyday normal use.

Wal-mart Super Tech Oil comes in a 15W-40 flavor for diesels that meets all the required diesel specs. It is probably a decent oil ( I use it in my VW that likes to drink it). It is not on Mercedes recommended list. But you likely used the gasser 20W-50 variety. Again, an acceptable oil, but it does not have additives that will suspend much soot. Without knowing how much soot your engine generates (probably not a whole lot, since it is a later car) it is hard to say when to change it. If it were me, I would change this oil at 2K miles and put some rated oil in next time. There has been a lot written here about soot and testing, please do a search and read up on it.

And, WalMart buys their oil from the cheapest source, more likely to be Murphy Oil than Mobil. Nothing wrong with that as long as it meets spec.

Rick

I use shell rotella T 5w40 full synthetic with "advanced soot control" from walmart...comes in 4 quart jugs for $15 each. It may be okay to use a 15w40 in the hot summer, but no way I am using that in the winter time here in Maryland.

I agree, 5W40 synthetic is much easier starting in the winter.

i use Chevron Delo 400...15w40

15w-40
 

I use 15W-40. Many brands such as Rotella, Napa, etc. Cheapest I've seen is at Menards & Walmart in 4 qt containers. Menards sells Rotella for under $8.

Expext oil to be pitch black after change.

I use oil that has a C rating. Usually Shell Rotella for my Powerstroke and Delvac1 for the MB.

Cheap oils
 

Turbo diesels should really have an oil rated to dissipate carbon particles generated by the turbo. Shell Rotella has Mack, Cummins, Detroit D. ratings, this is the sign. Chevron RPM Delo probably also but it is sold at truck stops, I've never seen it in a regular AP store. Mobil Diesel would obviously have late C ratings, I've never seen it either. Regular mobil 1 has a late "C" rating, but it's expensive and my engine is far from perfect, 285000 and the crank wasn't turned when the bearings were replaced.
I have experienced no crank wear in engines that run 20W(MS rated oils, really primitive), and .003" crank damage per 150000 mi in engines that specify 10W, (advanced SD or later oils) and I have quit running oil below 15W. Oils are so thin hot that I really like the 50W rating, if you don't have an engine that runs the oil so hot that the viscosity additive cakes up. (remember the 10W30 instead of 10W40 controversy, but that was SF rated oils, and they are up to SL now).
My 240D has no turbo, so I run the cheapest SL rated 20-50 I can find, currently Exxon Superflo from Big Lots.I meant to change to Rotella 15-50 last winter but was too lazy, and the car started cold at 17 deg F one night when I got called to work unexpectedly, on 20W oil.
The biggest mistake you can make (I did) is forgetting to fill the oil filter housing (if it's the same as the 616 2.4L) when changing the oil. Mine ran 45 seconds with no oil pressure. Very bad for the crank. I hope the 20W-50 was stuck on there like the glue it resembles.

Mistake
 

I filled once with 5W-30 cuz I got plenty of that for my gas cars. Not a good idea. Oil too thin and will leak/escape wherever it can. Obvious sign was thru breather on top of engine. Never again on the 300D. I think 15W-40 is good all around. Just get a block heater for the winter, if oil too thick.

I rarely, and I mean rarely, more like never - bring my cars to an instant oil change place. For some reason, something always gets messed up after (untightened drain plugs or caps or burning oil odor from drips).

So I stock up on motor oil and filters. I put the used oil in 3 gallon containers and bring it to the instant oil change place who are required to take and dispose of it.

Buy your filters online. They're cheaper and u get the german stuff.

I use Quaker State 15-40 all year around ( from Walmart) - it's recommended by Benz Canada, Our winter temp. in Sth. Ontario is about equal to yours.

Which grade do you use in Winter?

OIL Brand
 

I use only Shell Rotella,I get it at Costco .As stated before to each his own,most important thing is keep it changed.Good Luck Johnny:)