jmat...@attglobal.net wrote:
> jim beam wrote:
> > http://physicsweb.org/articles/world/15/2/7
>
> Shoving 0W20 down our throats to reduce C02 by millions of tonnes
> (its a British story) seems to be the future.
>
> Note that even 5W30 specs are more like 5W25 in actual grade, if
> there were such a thing. Also interesting that this story proclaims
> oil increases in viscosity with use. B.S., the modifiers break down
> and the oil reverts to its true state, which is thin, not thick.

Some "abuse" of oil is known to lead to oil thickening.

I know you're making up the "5W25" number, but there are variances
in the acceptable range for an XW-30 oil. The lower limit is 9.3
cSt at 100 °C, while the upper limit is 12.5 cSt at 100 °C. Mobil
1 5W-30 is 10.0, their "conventional" oil is 10.8, while the green
colored Castrol Syntec 0W-30 (AKA "German Castrol") is reported to
be somewhere over 12.

> This story is a tree hugger event.
>
> Still sticking with 10W30.

Some manufacturers (esp European) have come up with their own
approval lists or specs that are more than just the standard
(arbitrary) SAE weights. BMW LL-01 spec oil seems to be met
by a number of XW-40 oils, and some 0W-30/5W-30 oils that are
on the heavy end of 30 weight. The SAE scale is a very blunt
tool. An analogy would be that the manufacturer spec'ed a part
that weighs between 130 and 150 pounds, but the suppliers have
adopted a standard measurement of "light" from 120-140 pounds,
and "medium" from 140-160 pounds.