Change oil soon (& then some)

[Programmer]

What's ZDP ??
Lyndon.
----- Original Message -----
From: Greg Hermann <bearbvd at cmn.net>
To: <gmecm at diy-efi.org>
Sent: Tuesday, May 29, 2001 10:44 PM
Subject: Re: Change oil soon (& then some)


>
> >You're right Shannen--it's a thermal issue. The other
> >is under computer models, the reduced oil viscosity
> >pumps easier and "theoretically" provides better
> >fuel economy--less pump HP parasitic losses.
> >
> >Lyndon.
>
> >>
> >> Better grades of oil have allowed reduced engine clearance
> >> specs.  In turn, reduced engine clearances require "thinner"
> >> oil.  Oil of too high viscosity can cause the bearings to
> >> burn out.  I don't know whether it's th inability of the oil
> >> to carry heat away fast enough, or the inability of th oil
> >> to provide adequate lubrication.
>
> Thinner oil will yield a higher volume flow rate, and thus carry heat off
> more effectively. Thicker oil will generally give a higher film strength
> under extreme conditions-although some of the synthetics are an exception
> to this.
>
> Moderately tighter bearing clearances than what is traditional, together
> with a high volume pump and thinner oil can be a great compromise--& keep
> the bearings real cool--but the factories are going with really tight
> clearances, thin oil, and a lower volume pump so as to keep the parasitic
> HP down too. In this kind of a set-up--heavier oil will lead to too little
> flow of oil through the bearings (as a coolant) and things will fry.
>
> >>
> >> This can also happen in aluminum manual transmission
> >> gearboxes when the required ATF has been unknowingly
> >> replaced with traditional gear oil.
>
> Usually only in the ones with a teensy little oil pump with a
"microscopic"
> drive!
>
> NON-EP type gear oils will generally be OK in most trannies--the sulphur
> and chlorine based additives in the  EP (hypoid) type gear oils will
> corrode some parts in many manual trannies, though.
>
> Never seen ZDP additive hurt anything. And--oh BOY --does it give
> protection under extreme pressure conditions!!
>
> Greg
> >>
> >> Shannen
>
>
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