Single & Multiple Viscosity Oil and Other Stuff.

[jcmartin@xxxxxxxxx]

     When using multi-grade oil in my over hauled straight "8" engine,
I was using or losing oil & constantly adding. Some of the usage may
have been due to the gaskets and seals, although all were replaced. My
feeling is, the older engine mating surfaces are not so precisely
machined as
the newer engines & tend to leak more.  I returned to 30W detergent &
the problem has ceased.

     I empathize with the member who misses posts Re: 1981 models and
not being familiar with that model,  I do see
many excellent  posts on the 81.  If I were to own an 81 model, I would
remain a member. There are members on this list who know more about this
car than the company which built them and give freely
of their expertise & experience.

     Lastly, I note some of the posts I receive have the "un-subscribe"
trailer at the end & some do not. 

That's all Folks
Jim
1939 Custom Imperial Limousine C24

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• From: "D. Dardalis" <dardal@xxxxxxxxxxxxxxx>
• Date: Sat, 12 Jan 2002 19:38:08 -0600

At 11:15 AM 1/12/2002 -0800, you wrote:
>Isn't multi-grade oil the cold weight with additives to make
>it work differently when hot?  In other words, 10W-30 is SAE
>10 weight oil that acts like SAE 30 when hot.
>
>Seems like any additives would break down over time, and it
>would revert to 10 weight oil if you left it in too long.
Correct, but it will take a very long time and many-many miles for that to 
happen to a modern oil.  This is however one of the reasons that oils like 
10w40 (rather than 20w40) where there is a wide difference between the 
"hot" and "cold" grade may be best to be avoided for hard driven cars- they 
rely too much on the additives.  This is one of the main advantages of 
synthetics:  they rely very little in viscosity additives, so you can 
extend the drain intervals.

>Every owner's manual I've ever seen links oil to climate
>conditions.  If you're in a mild area single weights are
>great; for most of us with varying climates we need the
>cold-start advantage of multi-grade.

Yes, you will be fine with a single-weight 30w or 40w  if you lived, say, 
in Hawaii.  But even then, unless you plan to extend your drain interval, 
why suffer the heavier startup wear caused by the "hesitation" of the 30w 
to circulate when cold-started.  These type of oils are usually quite 
cheap, so there is also little incentive trying to extend your drain 
interval...
D^2

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