Re: [MV] Multi grade oil in a 6.2 Diesel

From: Jim (
Date: Mon Dec 16 2002 - 17:12:48 PST

    I wonder the same thing. Both my M35A2 and 5kw generator specify single
weight oils. From what I understand, multiweight oil is based on a synthetic
chemical chain which is how it can be different viscosities at different
temperatures. I've read that under the extreme pressures of a diesel engine,
that chain can literally break apart making a mess of what should be
lubricant. I've also read that some military engines have large "oil
burning" tolerences built into the piston rings, etc. Supossedly, the
problem with multiweight oil is that it can leave a residue behind after
being burned, sometimes a corrosive & abrasive residue. Not what you'd want
in your cylinders.
    Well, anyone familiar with the Internet knows you can't always believe
what you read. There are reputable M35 dealers putting multiweight oil in
the trucks. There are reputable generator dealers putting multiweight oils
in the generators.
    I know what's right in the philisophical world....single weight. If you
had a '43 jeep, I'd insist on single weight. In the real world, with a
modern engine, I'd say use the multiweight. Do you plan on keeping your
Suburban for 60 years? I'm pretty sure there's multiweight oil in the
equipment I bought, even if it wasn't "stock". When it comes time to replace
those lubes, I'm planning on multiweight.


> Hi all,
> I've recently picked up a Suburban with a 6.2 liter diesel engine in it.
> know it's not an MV, but that engine was used in HMMWVs, etc, right?
> Just a quick question on oil... I am in the middle of my first oil change
> for it, and I was about to put 15w-40 in it (since I stock it for the
> family vehicle) but found the placard recommends straight 30
> weight. 15w-40 is acceptable, but not the best...
> If I remember right "15w" in a multi grade means the oil will flow like a
> 15 weight cold, (w=winter) but like a 40 weight warm. I've always thought
> this "range" provided the best protection for the motor, but now I
> encounter a manufacture recommending a single viscosity oil.
> Is it a diesel thing? I'm in Southern California, so the lower temp
> performance isn't really an issue (hold over from my youth in Maine I
> suppose) but does a single weight actually out perform a multi grade?
> Thanks,
> Chris Davis
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