M1 5W-40 first time
 

I switched to M1 5/40 after running 15/40 Rotella for the past 10 years. I wanted to see if it would quiet the lifter noises. At first, the lifter noise seemed to increase. Not the loud clacking, but you could hear them all ticking at idle. However this cleared up after a good hard run. Now when I start it cold, there is just a little noise, not nearly so loud as before, and just for a few seconds. Then it quiets up to a nice Mercedes diesel purr. I am very pleased with this oil and it has only been less than 100 miles. I hear some people report more improvement after many miles.

My only question is, when summer hits here with 100 plus daily temps and non stop A-C use, will the 5/40 be too thin?

It seems to me that it must flow like 5W to get to the lifters so quick.

No.

Correct me if I am wrong, please.

I believe the first number is the cold flow rating of the oil. (5W-40 flows like a straight 5W oil when it is cold. When it gets hot it flows like a straight 40W oil.)

Based only on that it would seem like the oil would be fine year round. HOWEVER, I have no personal experience at this.

-Jim

This is correct. The only oil you need year 'round in any climate is either M1 5W40 or 0W40. That's it, no reason to use anything else and no reason to use one over the other except what's available at the time you are shopping.

Be cautious on your first oil change or two when running Delvac 1....it's a potent detergent oil and is likely to be doing major cleansing from years of running dino oil/sludge build-up.

When I converted my pickup over to 5-50 castrol I needed two oil changes in two months...
Now I run 9K per change with a new filter and requisite quart to fill the filter every 3K.
I have not yet converted teh 300DT over to synthetic, that's teh plan though.
-nB

Isn't the 0W-40 a CF oil and the 5W-40 a CI-4 oil?

Yes, you're correct. OTOH, the 0W40 meets the MBz lube requirements, the 5W40 does not due to additization levels.

Lube oil mfrs can pickup the CF rating without any additional certification and sell the product in many areas of the world where the newer API truck oils aren't permitted.

My bottle of Mobil 1 5W-40 reads CI-4, SL/CF Certified.

So.... which oil is the correct oil to use? (in a E300?)

I recently went to my dealer for some parts, and asked about oil. The parts guy says they (this dealer) no longer recommends 0W-40 for the E300. They are using 15W-50. I asked what about the 5W-40, and he shrugged and said 15W-50.

Of couse none of this makes me feel any better. I use 0W-40 is most of my other cars, so I put 0W-40 in my E300 (MY99). I personally don't want 50 weight anything around my garage after losing some camshafts in one of my old cars. (was using Castrol 20W-50 at the time)

I was planning on using 0W-40 untill the 5W-40 becomes available in my area. (eastern PA)

Personally I would NOT use a 15W50, especially not in winter in PA.

The 5W40 is what I have used in my '98 and what I would recommend you use in your '99. Either of the 0W40 or 5W40 is CF rated which is diesel approved but the 5W40 is CI-4 rated too, which is a higher level of diesel rating.

The confusion might be because the CI-4 is rated for ultra low sulfur fuel which is what we are seeing now...so for that reason I would stick with the CI-4 rated 5W40 from here on out.

FYI - While I have not seen the new M1 5W40 on the shelf at Wal-Mart yet I was able to order it by the case from my local NAPA store last month and they got it in one day from a local oil distributor...it is the "Turbo Diesel Truck" Oil which used to be the "Truck/SUV" oil. From everything I have seen and read it is the exact same oil, just labeled differently now but if you need it just order some. A case is only 6 quart bottles.

These weights the same for the 617 for synth?

I also use 5W40 synthetic in my 616 and 617.

I use the 5w40 expensive stuff in my car, but we use the 0w40 stuff in the '83....both seem to run the same/not care. They do run smoother than they did on Rotella dino 15w40 though. Quite a bit smoother, and starting in the cold temps has been awesome!! Massive difference in crank speed. :D

Yes, the CI-4 rated oil (5W40) is backward compatible with any vintage MB diesel engine. I recommend having an oil analysis done by Blackstone or any other lab to determine the optimum interval between changes since the recommended interval is probably very conservative for synthetic oils.

I know I felt uncomfortable about running the oil 10K miles between changes but the oil analysis I had done at 8K miles last time showed well below average contaminants and they recommended I try a longer interval next time, so I will shoot for 10K miles. My FSS says I can go 12K but I doubt I would ever stretch it that long.