Ok, We need a test case. I hear and understand what
D2 is saying and actually agree with his words. I;m
struggling with the difference between the theory that
D2 correctly describes and what I perceive to be the
real world.
In my experience, if you have a car that smokes A
LITTLE, especially at startup, then running Vavoline
40 or even 50W racing oil (non detergent) will greatly
reduce the smoking AND increase oil pressure. The
downside is that when it is VERY COLD (40 or less) it
seems a little harder to crank and oil pressure does
not pop up quite as fast but still pops right up.
What works for me may be because I have rather sedate
driving habits but based on what D2 said, my solution
would actually be better for hard driving except
possibly for a few seconds at startup. After all,
it's RACING oil.
A car which smokes probably has extra clearance in the
journals and the heavier oil seems to take up some of
the slack hence higher oil pressure. Yep the heavy
oil can get SLOOW when cold but my thinking is that it
will also stay in place on the journals while the
pressure is coming up. Anyway, in 37 years of messing
with old cars, this has worked for me and saved me
several rebuilds because I won't drive a smoking car.
I've never had an engine seize or develop a knock.
If it doesn't smoke, has decent oil pressure, and has
not other mechanical problems, I'm perfectly content
to let my money get smaller in the stock market rather
than building an engine. However, this is MY OPINION,
what we need is a test of sorts.
I'm willing to make this offer to ONE person. If
someone has a car that smokes a little (enough to be
noticable and be able to tell if it smokes less after
the test), is due for an oil change, and normally runs
a multigrade detergent oil change it and put in
Vavoline 40 or 50W racing oil (Autozone, walmart,
advance, etc). The racing just means non detergent.
IF it does not, IN YOUR OPINION, reduce smoking, I'll
pay for the oil and filter and you can change it back
to whatever you want. This does not include labor so
I guess I'm looking for a do-it-yourselfer.
This will be first come only to the FIRST person who
emails me privately. When I get a volunteer, I'll
post who it is and we'll await the results.
Kerryp
--- dardal@xxxxxxxxxxxxxxx wrote:
> In addition to Mike P.'s comments, the reason why
> 5w30 is not recommended in
> hot weather is the following. The 5w30 uses a 5w
> base stock and in order to
> get to the 30w hot viscocity, they need a LOT of
> viscocity additives. Since
> these additives deplete with extended hot operation,
> this oil will get thinner
> faster. If it was a synthetic, it would rely a lot
> less on the additives, so
> it would be OK. Mobil 1 has a 0w50 for super cold
> climates and hard driving.
>
> Clarification for those somewhat confused with these
> terms: Fisrt of all,
> viscocity is a term that shows how easily the fluid
> flows. The higher the
> number, the slower the flow, but the better the
> "lubricity" of the oil, or its
> ability to protect sliding surfaces. A 10w, or 20w,
> or 30w is basically a
> relationship between temperature and viscocity. All
> oils loose viscosity with
> increasing temperature, and each number designates
> this relationship for a
> conventional mineral base stock (base stock=just the
> oil, no additives). Then,
> sometime just after WW2 they came up with multi
> weight oils that thanks to
> these tiny little additive molecules that expand
> when they get hot, they
> managed to reduce the rate at which the oil looses
> viscosity with increasing
> temperature. These additives are poured into the
> low number base stock (ie 10w
> to enhance it into a 30w for 10w30). So, now, if
> you made a graph of
> temperature on the x and viscosity on the y, all old
> type of single weight oils
> would be a bounch of down-slopping paralel lines,
> with the heavier oils higher
> up. The multi weights would still be down slopping,
> but less so, and would
> intersect the single weights (hard to invision
> without a picture). As a
> result, they had to come up with a different method
> to define the viscocity of
> the new oils. So, a 10w30 according to the new
> naming system would have the
> vicocity of an old 10w at 32F, and at 212F, while
> its viscocity would be much
> less, (more than 5 times lower than at 32F), it
> would be comparable to
> a "conventional" 30w. Further, as the temperature
> keeps on climbing, the
> viscocity loss will be far lower for the multi
> weight, a very important factor
> when it comes to lubricating the piston rings at TDC
> (the cylinder liner at TDC
> will reach over 250F even for light loads and far
> hotter at high speeds and
> loads). This resistance to viscocity loss with
> temperature is
> called "Viscocity Index" and that's one of the huge
> advantages of synthetics
> (Mobil 1 15w50 is one of the best). That's one of
> the reasons why synthetics
> are superior for hard driving, and multi weights are
> superior to single weights
> for ... any driving!
>
> D^2
> Quoting Rob P <fristpenny@xxxxxxxxxxx>:
>
> > I was checking my owner's manual & it has that
> generic temperature to
> > oil
> > viscosity chart.
> > If the 10 is the "cold" weight and the 30 is the
> "hot" weight, then why
> > is
> > 10w30 recommended for warm weather and 5w30 is
> not? It seems to me that
> > they
> > should be the same as far as heat is concerned. Do
> I have it backwards?
> > Rob
> >
>
>
>
>
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