0W-40 in 1970 Cadillac Eldorado

Steve wrote:
>
> OK, I swore I wouldn't respond again, but this is just too much.
>
> jim wrote:
>
> >The math is based on a simplistic model that is little more than
> taking 2 points
> >and drawing a line thru them.
>
> Its not a line, its a curve.

Right it is a curve not a line. And you haven't a clue as to what the formula
for the curve is in reality. But that doesn't stop you from pretending you are
making a mathematical calculation. All you have really done is read some glossy
brochures and are parroting the buzzwords that you read therein.


>
> But apart from that the "simplistic model" also happens to be EXACTLY
> correct for a Newtonian fluid, which is precisely what defines a
> straight-grade oil (no viscosity index improvers are permitted in
> straight-grade rated oils). Therefore, the only deviation from the model
> in the "real world" will be for the non-Newtonian fluid, which the
> multi-grade may or may not be depending on whether it has VII additives
> or not. Assuming it does, then it's viscosity will always be higher at
> high temperatures and lower at low temperatures than the Newtonian fluid
> up to the temperature at which the VIIs disintegrate, but by then both
> oils are oxidizing as well! Assuming that it does not have VIIs, then
> the "2 point" model is also correct for *it* at the high end (the low
> end may still be non-Newtonian because of pour-point depressant
> additives) and the two curves will never cross again above the

What an idiot. If you actually did have even a smattering of understanding of
the math you would recognize that I am saying the 2 curves never cross - that is
in most comparisons the 30 weight is always going to be thicker than the 10w30
at any temp that you might find in an engine crankcase. I don't know (and
neither do you) what the formula is for either curve but it is obvious that they
do not intersect.
Since you don't actually have a precise formula for the curve for either type
of oil it is just babbling nonsense when you claim you can prove your point
using mathematics.



> temperature at which the two fluids have equal viscosity (which in the
> example is already BELOW the 100c benchmark).

Maybe for some particular well chosen examples it will cross at a point below
100C. But in general if you compare what is most commonly available on the
market and what is commonly used in engines that won't be the case.

It is not as if all oil comes in perfect discrete steps of 10 20 30 40 weights.
These are categories describing a range. And even in your fancy brochure that
you offer as proof, there is a disclaimer to that effect.


>
> Duh.
>
> > What measurements? You have provided only 2 measurements for one particular
> > brand and that comes with a caveat that you may see some variance from the
> > measurements in the actual product. You are talking about one particular brand
> > of synthetic that has a tiny tiny share of the market.
>
> Chosen only because they make their data readily available and popped up
> first on a Google search. It also happens to be representative of all
> PAO-based synthetics in this regard, there's nothing special about it.


Nothing special except it is not what is in most engines on the road. And in
part that is why it costs more than what most people use.



> In fact in doing a little more research, that brand's multi-grade oils
> are apparently considered in the thin side and prone to shearing for
> their rating, so in that sense they are a bad case for my argument. Pick
> any brand you want, or pick a different brand of straight from
> multi-grade. Go ahead. Find a counter-example! Please!


You mean I should go find my own glossy brochures?




> Its quite likely
> that you can find at least one combination of oils that meet your
> criteria, especially since so many of the synthetic single-grades could
> easily qualify as multi-grades if dual rating were allowed. I didn't
> find such an example, but then I didn't go looking very hard for the
> oddball counter-example that may be out there.
>
> > That is pretty thin soup
> > you are calling proof.
> >
>
> At least I produced actual numbers instead of just waving my hands and
> saying the same thing over and over Lloyd Parker style.

Who is loyd parker? Another wannabee mathematician?

I'm not the one that made the bogus claim with nothing believable to back it up.
I'm perfectly happy with the information I get from observing a pressure gauge
or watching as it pours thru an opening. You on the other hand keep insisting
that the crap you read in glossy brochures is mathematical proof. Did it ever
occur to you that no company ever puts anything but the information that casts
them in a good light in their advertising literature? So if a company does make
a product that is a cut above average they are going to try to promote that as
selling point and put it in their advertising.



> Or talking about
> how you "notice it when it drains out of the pan," which means that its
> already well below the 100C benchmark for one thing, and I seriously
> question your eyeballs as an accurate measure of viscosity for another.
> If my soup is thin, yours isn't even soup yet.
>
> I'm really done this time.

HA HA HA

-jim