Mobil 1 0W-40 or 5w-40 in 617
 

I noticed that Mobil recommends 0W-40 for the W123 diesel motors but since it has a lower diesel spec than 5W-40, I emailed Mobil asking which one was really better. It took a couple of tries before I got something other than the blanket answer of either would work. Here is the response that I got:



Ron,

The Mobil1 Turbo Diesel Truck 5W40 motor oil would have better soot control and be the best choice for diesel engines, drain intervals would be the same.

-MJ


Ron wrote:
> I know that either product meets all of the requirements for the
> engines, but which one would protect the engine better or have the
> longest oil change interval? Will one or the other handle more soot
> loading? Would there be any difference in deposits in the combustion
> chamber?
>
> Thanks,
>
> Ron
>
>
> -----Original Message-----
> From: ExxonMobil [mailto:mobilproducts@ourdataworks.com]
> Sent: Tuesday, June 09, 2009 10:36 AM
>
> Subject: (no subject)
>
> Ron,
>
> Either product can be utilized can be utilized in both of these
> vehicles without issue, they meet all the requirements for the older
> vehicles that you have listed. So it may very well come down to what
> is easier for you to locate and purchase. The Mobil1 0W40 motor oil
> meets API "SM/CF"
>

Use the 5w40. The 0w40 oil is almost a 0w30, wheras the 5w40 is well into the 40 weight range.

When I used the 0w40 oil in my TDI the engine sounded like it was cold all the time. I stick with 5w40 now (the 0w40 oil is specifically approved for my engine though)

-Jason

Yep, use the 5w40.....the 0w40 is too thin. It makes the 617 sound clattery (probably not a good thing)

sounds like a sales pitch to me. I just stick with 15W-40

0w20 really lets the bearings and rods sing..

In colder climates the 5w40 is a great thing to use, it cranks over much faster in the cold temps....and oil pressure comes up faster. I'd especially recommend it for the colder climates.

Some of the VW TDI guys started using 0w40 when it first came out and reported high metal content in their oil analysis.

I agree. I don't use 15W-40 any more even in the summer. It's usually Rotella 5W-40 or Mobil 5W-40 year round in my cars. Since I don't go with ultra long drain intervals, I more choose brand between the two by cost.


FYI, in an emergency I have found that most Mobil dino oils for regular passenger cars have at least a CF rating. Most other brands are only SM (gasoline only). If I was stuck needing a top off, I would have no problem using any Mobil 10w-40 oil in my W123s. It's got to be better than any diesel oil from the early '80s.