I'm ready to change oil on my 300 SD.

What's the recommended oil for summer temps? I was told I could use 10w40, but that 20W50 is a winter oil?

I bought the case of SAE 30, thinking it'd be a good year round blend. I'll bring it back if not. What does the collective voice of diesel experience say?
Thanks!

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83 SD 143 K miles
93 Grand Caravan 130K miles
92 Buick Regal (winter car)

and take the 30w back. After reading all the oil related posts you should have an idea of the different oils that are out there that are acceptable.

The only unanimous opinion you will find here is to

**CHANGE IT HOT AND CHANGE IT OFTEN!!**

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Jim

There are some excellent oils that are specially formulated for diesel engines. These are called Universal grade oils and have added cleaners and soot dispersants.

Examples of these are; Shell Rotella T, Chevron Delo 400, Mobil Delvac and Mobil Delvac One. You usually won't find these at your local parts house. If they cannot be found at Wal-Mart in your area, try the truck stop out on the highway.

My 240D original engine went 380,000 miles on Cheveron Delo 400 Multigrade 15W40 year round.

At the very least you should check the label of the oil you choose to ensure that it has a "C" rating, e.g., CF, CG-1, etc.

With the great lubricants that we have available these days, there is really no need to change weights from winter to summer unless you live in the arctic circle.

Good luck,

Greetings,

As Larry mentioned there are several great multigrade oils on the market specifically designed for diesel engine use, labeled as C, CF, CF-4 ratings for greater soot dispersal in diesel engines. Although, you may be like me and have a slight rear seal leak and just can't justify tearing the pan off at this point in time, I have resorted to using the dreaded Castrol 20W-50 for this Summer to slow my seeping seal down a bit. If you have no leaking oil problems I would highly recommend either Shell Rotella 15W-40 or Chevron 400 Delo 15W-40 for year around use. They both price out about the same and are readily available at most any discount stores like Wal-Mart. I personally use the Chevron Delo 400 when the weather starts getting back down to a 60 degree or below average where I live. If you look at your manual it probably shows grades of oils and their temp ranges for suggested use. My manual on this '80 300TD still list SAE oil types as acceptable oils and thus using the Castrol 20W-50 during the Summer meets Mercedes light duty diesel requirements for this engine when it was built. Since that time some 22 years ago the oil companies have developed different rated oils to perform or clean better than others in particular engines, hence the "C" rated oils that are now recommended for diesel engines for greater soot removal. If you have no leaking or seeping seals stick with the diesel rated multigrades I listed above and you can't go wrong.

Sorry for Rambling, but it can become confusing depending on your particular engine situation.


Charles

I second the advise on Shell Rotella or Chevron Delo 15W-40. They are readily abvailable at any Walmart and they sell them in 1 gal. jugs, which makes it convienent for our 2 gal. oil pans. Every synthetic oil I have seen has a "C" rating, whereas only a few "dino" oils have this rating. Rotella and Delo being 2 of them.
Oh yeah and the other thing I second is the "....hot and often" regiment.

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1999 MB SL500 (110,000 mi)
2004 Volvo V70 2.5T (220,000 mi)
2014 Tesla Model S 85 (136,000 mi)
MBCA member

"Change it often " in not unanimous unless you consider every 10,000 miles often. I have been driving my '80 300SD for 120,000 plus the 114,000 it had when I got it and it still goes 10,000 miles without adding oil and runs perfect. Of course I use synthetic oil plus a little PTFE
additive.
P E H