OT GM AND SYNTHETIC OIL

ACEA ratings are European and therefore may not be quoted everywhere.
The Valvolene probably meets MB229.1 or even 229.3 specification and
therefore also meets ACEA A2 or A3.
The oils spec sheet is where you will find the most comprehensive
information.

By the way, I hope you do not infer that just because certain
viscosity grades of Mobil 1 are to a certain standard, then it
follows that the same viscosities from other manufacturers have the
same limitations or meet the same standards? It does not follow. The
viscosity met by an oil is mostly dependant of the performance
standard met, although certain standards may have a parameter set
where only a certain range of viscosities are suitable to meet the
standard.
I hope that is clear.

Huw

 

I agree.

Huw

 

Is there any comparison that is meaningful on that site where the oils
are not drained for the more normal [for M1 0w/40] 12000 to 15000
miles or more as in a BMW or Mercedes engine?

Huw

 

Another important point is that before the engine can warm up, it must
first start up!
Oils with lower "cold" viscosity are engineered that way in part to
provide better lubricity at low temperature so that the other part of
the automotive power plant, which is operating at greatly reduced
efficiency to begin with, has minimum resistance to spinning the
flywheel. (the "cold cranking power" of a typical battery at 0 deg F
being about 25-35% of what it would be at "room" temperature)

I leave it to the uninitiated reader to imagine the excitement attendant
on attempting to jump-start a vehicle at -15 deg F. I can and have!
(Done it, not just imagined it!)
-psmith (in New Hampshire)

 

Yes, there are other UOAs there where the M1 0w-40 has been run for 10K or
more miles, and at that point its viscosity is back to a 40 grade, but
you're missing my point. My point was that it is not shear-stable because
it thins (as proven by the link I posted previously), and then thickens back
up. While these fluctuations take place, sludge gets deposited inside the
engine. I'd rather have an oil that stays in grade throughout its life.

Cheers,

Pete

 

You are fairly obviously confusing a variation in viscosity with shear
stability. When an oil loses its viscosity due to a breakdown of shear
stability, that is that the molecules have 'sheared', they do not
regain that viscosity. It is usually a relatively sudden and permanent
situation where the whole lubrication performance of the oil is
compromised.
This is not the case going from your description above.
This oil [0w/40] is tested and approved for longer than normal service
use. Part of the standard is for shear stability and for the ability
to keep contaminants in suspension for a sustained period at high
levels under severe service. The reason that this oil meets and
exceeds the higher standards is because it exceeds the Standard for
these parameters which are MB229.3 and ACEA A3, also BMW Longlife. The
other oils in the Mobil 1 range do not meet and exceed these Standards
and are therefore inferior in this respect.
I would not expect shear stability per-se to be a problem over very
extended drain intervals in any viscosity or performance standard of
Mobil 1. It is likely to be the detergency and ability to neutralise
and suspend high levels of contaminants which compromise their
performance at extended intervals.

Huw

 

Well why not just say that 5w/30 is best for all-year-round use in
that climate because there is no advantage to be gained from a 10w/30
in Summer but there is a disadvantage in Winter?

Huw

 

.. The

That didn't read quite right! Substitute "dependant" with INdependant.

Huw

 

In

Huw... Puleeeeeeeze! That's like saying all brands of extra virgin
olive oil taste the same. ;-)
--

* Philip

"I'm dreaming of a white Christmas,
Just like the ones I used the ones I used to know"
-Bing Crosby

 

But why bother with two oils when a 5w/30 will be ideal for both?

Huw

 

Haven't really thought about it too much, but watching your neighbour
freeze in a snowbank kind of takes the bloom of the rose!

Dan