[s-cars] Re: Mobil 1 0W40

[CyberPoet]

Jonathan,

   A multi-weight synthetic oil characterized as X-wY, where X is a
numeric value (examples: 0/5/10/20/30) and Y is a higher numeric value
(examples: 10/20/30/40/50) is stated to be:
X is the actual base viscosity weight of the oil (compared to a
'traditional' dino oil) for pumping purposes, and Y is the
characteristic viscosity standard of a similar quantity of
'traditional' oil at which the labeled oil as a test sample will
perform before viscosity loss (due to thermal breakdown or sheer
forces). Y is not to be confused as an actual weight of the oil at any
temperature in a 0-wXX oil.

This means that a 0-w40 synthetic has a pumping viscosity (weight) of
zero (reference light oil weight), but will not break down until the
standard breakdown point of a 40 weight 'traditional' (i.e. - non
synthetic) oil would. It does not mean that the oil actually alters
it's weight as it heats, and only that zero weight is relevant for
pumping purposes. If the auto manufacturer recommended oil-usage
specification for a specific model calls for a 20 weight oil in your
ambient conditions, then a 20-w50 is suitable, but a 5-w30 is not. With
tighter tolerances on machining and new engineering practices in the
German auto industry (among others), many new German (& other) cars are
shipping with a 0/5/10 base weight specification (or similar).

Most synthetic formulations use an uncurling long polymer chain that
changes the effective viscosity (upwards) as the temperature rises, but
the reference weights listed on the package do not refer to that in any
sense, as the API's standards for the rating does not include that
information. The real benefit of a pure synthetic isn't so much the oil
itself as the virtually absolute lack of impurities that can be
generated when formulating a pure synthetic oil. Added benefits include
higher detergent amounts stabilized, higher vaporization temperatures,
longer stress life span before sheer-induced failure. Many of the same
benefits can be gained by mixing traditional oils with synthetics for
those on a budget, since the API specification requires that all
synthetics be 100% mixable with all other API-specs oils on the market.

For owners of older vehicles whose cars do not have these new light-oil
designs, too light an oil can induce pumping problems, driving static
(idle) oil pressures down and possibly starving the engine for oil.
Additionally, older engines can frequently have sludge deposits, which
introduction of a synthetic oil can suddenly loosen because of it's
detergent content and flow characteristics, and such sludge is often
formed around seals and gaskets, inducing the impression in some that
synthetics can cause an older engine to leak (actually, the engine
would have leaked anyway -- gunk was saving it from leakage!). This
same gunk, suddenly freed, can block oil passages and reduce the
effective oil pressure to the engine (or even block it all together),
which is why when changing over on an older engine I recommend using an
oil flush product before hand (specifically to help remove such
varnishes and sludge deposits). One final word on when not to use
synthetics -- during initial engine break-in of an engine if the
manufacturer did not specify a synthetic oil.

One other related note: Castrol at one point decided to blend a
synthetic and non-synthetic oil and label it as a synthetic oil without
reference to the fact that it was a blend. They had figured out how to
match additives to traditional oils and get them to perform as if they
were pure formulated synthetics (the conversion process cost them about
50% of the product cost of generating a pure synthetic). Naturally,
they were promptly sued by a competing automotive oil firm (I think it
was Mobil; the plaintiff  felt it was a deceptive practice). The result
of the lawsuit with Castrol as the defendant, was an official court
decision that mix-blends can still be claimed to be synthetic if they
contain a synthetic portion, without regard to the actual percentages
of synthetic vs. traditional dino oils. The consequence has been that a
number of firms are now blending traditional and synthetic oils and
labeling them as synthetic oils.

Now, before you get on your high horse again, go back and read my
original posting: based on MY PERSONAL, I recommend that anyone using
this oil in an OLDER CAR pay particular ATTENTION to their Oil Pressure
Gauge. I did not say "hey, don't use this!" I didn't say "this stuff
sucks." I didn't lambast it at all. I think synthetics are a great
concept, where ever feasible, and I use a similar product in my
motorcycle (a full synthetic 5-w50 Motorcycle oil -- and yes,
motorcycle oils are different than car oils) -- which provides a
noticeable power increase at the rear wheel (not a small feat from a
such a small investment).

Best Wishes,
=-= Marc Glasgow

PS - feeling really ambitious and a bit stupid? Get a dozen metal cans
(unpainted), pour half a cup of each of a dozen brands of motor oil
into them, then stick them in an oven (in a well ventilated space!) at
400 degrees fahrenheit. Check back every 15 - 30  minutes and tell us
which brand and blend performed the best... It's a most interesting
experiment and you'll be very surprised at the results.

On Sunday, March 2, 2003, at 10:44 PM, J. Khang wrote:

>> Some words of caution to those of you with older
>> (pre-1998) Audi's (or other brands), especially
>> those with higher mileage counts: this oil is
>> thin enough that your engine may have difficulties
>> in maintaining proper oil pressure at idle.
>
> Oh dear, it's this one again. OK, let's go over what
> the viscosity ratings actually mean again.
>
> A 0W oil has a kinematic viscosity of 80 cP at 40C. A
> 40 weight oil has a kinematic viscosity of 14 cP at
> 100C. Therefore, a 0W40 is thicker at room temperature
> than it is at operating temperature.
>
> Still think that a 0W oil is too thin? Why?
>
> Jonathan
> '96 S6