<VV> Multi-grade vs. 'straight weight' oil

[Mark Durham]

Charlie, as a word of explanation on oil weights, the 10 in 10W40 means
additives make the 40wt oil work like a 10wt oil when cold, so it flows
faster to build oil pressure faster, then as the oil warms up, it
thickens to to 40wt for normal running. Mark Durham

Sent from my Windows Phone From: Charles Lee
Sent: Tuesday, November 01, 2011 10:49 PM
To: Mark Durham; Frank DuVal; virtualvairs at corvair.org
Subject: Multi-grade vs. 'straight weight' oil
I believe that the multi-grades that "exceed the 30wt minimum standard in
every way" are current blends, and not the oil that was available when the
car was new?

The "10" in "10W40" is the "cold" weight, while the "40" is the weight that
will thin out when the engine warms up?

Where is Richard's paper on this? Apparently I need to brush up, right Matt?

Charlie


-----Original Message-----
From: Mark Durham [mailto:62vair at gmail.com]
Sent: Tuesday, November 01, 2011 9:24 PM
To: Charles Lee; Frank DuVal; virtualvairs at corvair.org
Subject: RE: <VV> Is 'straight weight' oil BETTER or just sufficient (and
easier to find) ? (was Corvair Tall Tales)

Gents. Read Richards oil paper. The corvair engine was designed around
a straight wt 30 oil, as a minimum standard. It was the prevelant oil
of the time. Multi-grades work better because they provide lubrication
faster on startup when most wear happens. The recommended multi-grades
exceed the 30wt minimum standard in every way. Mark Durham

Sent from my Windows Phone From: Charles Lee
Sent: Tuesday, November 01, 2011 8:31 PM
To: Frank DuVal; virtualvairs at corvair.org
Subject: <VV> Is 'straight weight' oil BETTER or just sufficient (and
easier to find) ? (was Corvair Tall Tales)
I'll have to review all those posts, but I don't believe it was determined
that multi-grade is just easier to find and "just as good" but not
necessarily better than straight weight?

When was this discussed? (so I can limit my search through the digest)



-----Original Message-----
From: virtualvairs-bounces at corvair.org
[mailto:virtualvairs-bounces at corvair.org] On Behalf Of Frank DuVal
Sent: Tuesday, November 01, 2011 6:51 PM
To: virtualvairs at corvair.org
Subject: Re: <VV> Corvair Tall Tales ~ Is 'straight weight' oil better ?

Urban legend!

Use a good quality multigrade oil for best results. See Richard's web
site for more explanation.

http://www.widman.biz/uploads/Corvair_oil.pdf

This has been covered many times here.

Just avoid the sunburst in the front of the bottle is also a recommendation.

I used to use straight 30 in the summer, but stopped that over 15 years
ago. I'm a slow learner, but you beat me!

Frank DuVal

On 11/1/2011 8:54 PM, Charles Lee wrote:
>
> As I remember, Corvairs required 'straight weight' oil, 30W or 40W, and
> multi-grade was taboo?
>
> Was it an 'urban legend' or was it true that, when 'generic' mechanics put
> multi-grade oil in Corvairs, that the engine heat would break the oil down
> and cause lack of lubrication and overheating ?
>
> Today's multi-grade oil is better, but is it OK to use it in a Corvair?  I
> look for single weight, but it's harder to find.
>
> Charlie
>
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