Re: engine oil question

[ben dover <sujitroy@domain.elided>]

Thanks for the info.  Yes! I'm in California. So, the only major
difference between them is operating temperature range? The upper end
of 10w-40 and 20W-50 is the  same, so I'm quite safe using the 10w-40. 
I was more concerned about peoples findings and what they reported and
recommended.
 Thanks for the info about the head.  I'm releaved somewhat.  There is
a leak in the cylinder head gasket which very close to the timing
cover. Maybe I just need to torque up the head.  
On the subject of oil, after 3K miles on all my cars the oils been
black.  I'm a regular user of Chevron 10w40.  Should I change brand?
Sujit

--- PGAHOWELLS@domain.elided wrote:
> Hi
> The ambient temperature in which you are operating
> is the big deal
> 10w-30   -20 to+20 Centigrade
> 10w-40  -20 to >+20 Centigrade
> 20w-50   0 to >+20 Centigrade
> The ROM mentions API SE. Most of todays Engine oils
> are higher spec.  SE was 
> followed by SF and then SG  and I believe there is
> even an SH now. These 
> advances refers to the increasing ability of the oil
> to withstand reduction 
> in the power of its additives, allowing it to last
> up to 12000 miles in 
> modern engines. It is not recommended you keep it in
> that long in a Stag, 
> because putting it crudely, it goes black in a Stag
> after 3000 miles which 
> messes up its qualities. In a modern lowish mileage
> engine after 9000 miles 
> it still looks fairly clean.
> Are you in California. Then if it never goes below
> freezing use 20W 50. The 
> numbers refer to the viscosity range. 20W is too
> viscous for quick starting 
> in a sub zero winter temperature, hence for that we
> go down to 15W or 10W 
> (brrrrr).
> If you really want to know a lot more about this
> subject then you need to 
> obtain input from a qualified lubricants
> engineer/chemist.
> Peter H
> 



===
Sujit Roy
786 Erie Circle,
Milpitas, CA 95035 U.S.A.
E-mail: sujitroy@domain.elided
1971 Triumph Stag - project
VTR Member #12466

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