does oil "expire"

On 7/27/2011 2:14 PM, ps56k wrote:
> Here's another follow on question on oil.
>
> My son has a motorcycle,
> and his browsing/reading
> led him to use "Rotella T6 5w40"
> which is a diesel engine oil - for his motorcyle....
> Comments indicating it would hold up better in the high revs engine.
>
> SO - how is this diesel Rotella T6 5w40
> different than a car engine 5w30 ?
> What would happen if you used it in a car engine ?
>
>

If (big IF) the gas engine maker specifies a 5W-40 (non do that I know
of) then it would work just fine probably. Diesel rated oil has better
detergent capabilities mostly which are needed to keep the soot in
suspension (why diesel motor oil turns black very quickly--not an
indication that the oil is bad, either).

However, modern gas engines are not rated for 40 weight oil, and you are
likely to damage some parts using the wrong oil. Old engines would
probably be OK with it--modern ones much less happy.

As for the motor cycle, I can't answer, you didn't give enough information.

--
I'm never going to grow up.

On 7/27/2011 12:14, ps56k wrote:
> Here's another follow on question on oil.
>
> My son has a motorcycle,
> and his browsing/reading
> led him to use "Rotella T6 5w40"
> which is a diesel engine oil - for his motorcyle....
> Comments indicating it would hold up better in the high revs engine.
>
> SO - how is this diesel Rotella T6 5w40
> different than a car engine 5w30 ?
> What would happen if you used it in a car engine ?
>
>
Disclaimer: I am not familiar with that specific formulation of Rotella
T.

Folklore back in the 60's for those of us with high revving european
sports cars was that indeed the Rotella T diesel oils were superior to
the ordinary automobile oils for these engines that otherwise had a
habit of burning oil or developing cold engine bearing rattle. The
Rotella T oils were listed in the owners manuals as one of many
recommended oils.

In article >,
ess says...
>
> ps56k wrote:
> > Here's another follow on question on oil.
> >
> > My son has a motorcycle,
> > and his browsing/reading
> > led him to use "Rotella T6 5w40"
> > which is a diesel engine oil - for his motorcyle....
> > Comments indicating it would hold up better in the high revs engine.
> >
> > SO - how is this diesel Rotella T6 5w40
> > different than a car engine 5w30 ?
> > What would happen if you used it in a car engine ?
>
> Different formula for higher temperatures.
> http://en.wikipedia.org/wiki/Motor_oil
> Gas engines run a lot cooler than diesel and oil
> ratings are based on the temperature band.

In any case, Rotella T6 is rated API SM, SL, and SH, and JASO MA, which
means that it meets the warranty requirements for just about all cars
and motorcycles manufactured prior to the 2011 model year (but do check
your owners manual and make sure).

For 2011 there's a new API standard, SN, and it won't meet warranty
requirements if that is specified.

Note that the SH rating means that it's also OK for older models that
need ZDDP to avoide premature and excessive camshaft wear.

On 7/27/2011 1:14 PM, ps56k wrote:
> Here's another follow on question on oil.
>
> My son has a motorcycle,
> and his browsing/reading
> led him to use "Rotella T6 5w40"
> which is a diesel engine oil - for his motorcyle....
> Comments indicating it would hold up better in the high revs engine.
>
> SO - how is this diesel Rotella T6 5w40
> different than a car engine 5w30 ?
> What would happen if you used it in a car engine ?
>
>
According to my "oil expert" (this is the same guy that gets to do my
engines) The diesel oils typically have modifiers to reduce cam lube
wear that are missing from the latest SAE oils. So any engine running
plan old cams will run longer on either diesel rated or the SH rated
oils. After that, I think there is a lot of folklore unsupported by real
evidence. The race guys are REALLY into things like that, gives an
opportunity for evidence based folk to really take charge.

On 7/27/2011 6:02 PM, DougW wrote:

> Gas engines run a lot cooler than diesel and oil
> ratings are based on the temperature band.


You've over simplified that statement from the Wiki...
Generally (overall) diesel engines in fact run cooler
(as they are more efficient) and the higher temperatures are found in
the upper ring area.

It is a complex thing, so summarizing it can be difficult!


--
I'm never going to grow up.