Hey everyone quick question, about good ol motor oil. I have been using 20w 50 in my 300SD. I live in So Cal. I get my oil changed every 3k-3500 miles (try to get at 3k but sometimes just dont get around to it). This last time i changed my oil my car started running much better. Seem like it had more "pep" and that the turbo seemed to spool faster and just performed overall better. I have 215K on original parts.

Which is the best motor oil to use? Sombody recently reccomended to me that I use a brand called "rotella" designed for diesels which I wouldnt need to change for 10,000 miles. is this true? what do you guys use and how frequently do you have it changed?

(I did a search and I didnt find a straightforward thread on this basic but important topic)

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1985 300SD- 212K and running

No, 10,000miles is far to long to go on a non-synthetic oil.

3-5,000k miles is fine for dino oil and you can push up to 8,000 if you use a good quality synthetic (not rotella).

The oil brand does not matter. What matters is that it has a Cx rating on the bottle. Most 15W-40 and 5W-40 oils have that rating.
http://www.calsci.com/motorcycleinfo/API.html
http://www.api.org/certifications/engineoil/categories/upload/English_Oil_Guide.pdf

If you want to know what brand of oil to use, search the forum. Its a fiercely opinionated subject and there is no bad oil as long as it meets the C rating.

Thanks for the links. I am not really picky about which brand to use. frankly I dont have much of a brand loyalty (except MB of course) but rather want to use what is most practical and economic.

I hope I dont sound too stupid, but I really couldnt get much info out of those charts other than the fact that there are many types of diesel motor oils.

Should I be using 5w-40? 15w-40? 20-50? Orrrrrr...are any of these fine as long as it has one of the C(x-#) things printed on the bottle?

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1985 300SD- 212K and running

15W-40 is most common for non-synthetic diesel oils.
5W-40 is what most synthetic oils are.

If an oil is one of those two weights its most likely diesel rated.

My uncle uses "Rotella" in his 98' Dodge 3500 diesel truck and my other uncle uses it in his 85' Ford F250 diesel and his old 95' GMC Suburban diesel.

The 84' Mercedes 190D I just bought had the service records with it and the PO had been using Rotella in it for years. Not sure if its any indication, but looking down in the cap, it still looks like new in there... maybe that typical for a diesel anyway?

There are many opinions on oil usage however.

Oil analysis shows an average life of six months or 6000 miles for HDEO like Delo 400 or Delvac Super MX and therefore you can use either of them till 5000-6000 miles.

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99 Gurkha with OM616 IDI turbo

2015 Gurkha with OM616 DI turbo

2014 Rexton W with OM612 VGT

Depends on where you live, for temps lower than 0C, I would go for 5W-40 only and that means costly synths like Delvac-I or Delo Synth.

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99 Gurkha with OM616 IDI turbo

2015 Gurkha with OM616 DI turbo

2014 Rexton W with OM612 VGT

RotellaT is 5w40 and is cheaper than M1 or others. It's what I use in all of my cars.

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http://superturbodiesel.com/images/sig.04.10.jpg
1995 E420 Schwarz
1995 E300 Weiss
#1987 300D Sturmmachine
#1991 300D Nearly Perfect
#1994 E320 Cabriolet
#1995 E320 Touring
#1985 300D Sedan
OBK #42

I would look for somthing that has the ZDDP additive package. Our engines are flat-tappet engines and oil without this package accelerates camshaft wear. I am currently switching all of my vehicles over to Redline because of this.

Scott

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Scott
1982 Mercedes 240D, 4 speed, 275,000
1988 Porsche 944 Turbo S (70,000)
1987 Porsche 911 Coupe 109,000 (sold)
1998 Mercedes E300 TurboDiesel 147,000 (sold)
1985 Mercedes 300D 227,000 (totaled by inattentive driver with no insurance!)
1997 Mercedes E300 Diesel 236,000 (sold)
1995 Ducati 900SS (sold)
1987 VW Jetta GLI 157,000 (sold)
1986 Camaro 125,000 (sold - P.O.S.)
1977 Corvette L82 125,000 (sold)
1965 Pontiac GTO 15,000 restored (sold)

Good point, thats why I switched to Amsoil 15w40, Redline is probably a bit better though.

20w50 is to thick unless its for a racing engine. Go with something that has a 40 as the second number.

As far as when to change it, 617's put a lot of soot in the oil. You really shouldn't go much beyond 5k no matter what oil you use.


Rotella 5w40 is a great oil for the money, I used it in my 300SD.

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2016 Corvette Stingray 2LT
1969 280SE
2023 Ram 1500
2007 Tiara 3200

Not many people are aware of this. It wasn't a problem before because ZDDP was already in the oil. Also, most people don't drive cars with flat tappet engines. I use Redline in all my gearboxes too. I even have it in my lawnmower . Nothing wrong with Amsoil either.

Scott

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Scott
1982 Mercedes 240D, 4 speed, 275,000
1988 Porsche 944 Turbo S (70,000)
1987 Porsche 911 Coupe 109,000 (sold)
1998 Mercedes E300 TurboDiesel 147,000 (sold)
1985 Mercedes 300D 227,000 (totaled by inattentive driver with no insurance!)
1997 Mercedes E300 Diesel 236,000 (sold)
1995 Ducati 900SS (sold)
1987 VW Jetta GLI 157,000 (sold)
1986 Camaro 125,000 (sold - P.O.S.)
1977 Corvette L82 125,000 (sold)
1965 Pontiac GTO 15,000 restored (sold)

One of the members on here with a go fast boat told me about it originaly. He found out about it after losing 3 cams. Than I started asking around and its been causing havic with pumped up American engines, and classic cars. Lots of ruined cams, bearings, and valve trains.

Use a modern 5w40 ESP oil in your Gullwing and you will be rebuilding the engine within a few oil changes.

If you have a MB diesel older than a CDI, stay away from the new oils.

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2016 Corvette Stingray 2LT
1969 280SE
2023 Ram 1500
2007 Tiara 3200

I use Mobil Delvac 1300 15W40 Diesel oil

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1976 240D
1976 240D parts car
1970 220D daily driver

BTW, Redline uses a Polyol Ester base stock which most other synthetics don't. Ever seen the Mobil 1 sponsored Porsche race cars? They use Redline.

http://www.redlineoil.com/

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Scott
1982 Mercedes 240D, 4 speed, 275,000
1988 Porsche 944 Turbo S (70,000)
1987 Porsche 911 Coupe 109,000 (sold)
1998 Mercedes E300 TurboDiesel 147,000 (sold)
1985 Mercedes 300D 227,000 (totaled by inattentive driver with no insurance!)
1997 Mercedes E300 Diesel 236,000 (sold)
1995 Ducati 900SS (sold)
1987 VW Jetta GLI 157,000 (sold)
1986 Camaro 125,000 (sold - P.O.S.)
1977 Corvette L82 125,000 (sold)
1965 Pontiac GTO 15,000 restored (sold)

I use Rotella SAE 30 all summer my 300CD "Ela" loves it.

Will change to Rotella SAE 15-40 as temperatures drop below 50 F this fall.