Well, my Bentley manual also contains the driver's handbook for '62 -
'70. It was published and copyrighted in '69. It contains a chart in
it that mainly calls for multi-vis oil in the engine & gearbox, if you
can get it. Base viscosities vary as a function of ambien temps. It's
kind of amusing, really. It actually recommends various oils by brand
name. They wouldn't dare do that these days, huh? But the point is
that even way back in '69 they were using multi-vis oil. They didn't
change it 10 yrs later as you imply. Also, some of those recommended by
brand - say Mobil Special 20W-40 - must have been detergent oil. Anyway
it doesn't specify non-detergent.
Do you suppose the 5W was too thin for your OD because of wear?
That's what I suspect.
Here's something interesting that I didn't notice before in the
chart. Where the vis is specified for the carb dampers, 10W something.
So my 20W-50 isn't right for that app. Grr, hoist by my own petard! (G)
Cheers,
CR
ATWEDITOR@aol.com wrote:
> In a message dated 11/7/2003 1:50:30 PM Eastern Standard Time,
>ccrobins@ktc.com writes:
>
>
>> What I don't understand is why you don't believe that the guys who
>>designed and built the gearboxes/overdrives didn't know
>>what oil was
>>best to use in them.
>
>
> Well, since I was the owner in 1968 of a brand new '68 GT with the same
>gearbox and overdrive
as the later years and my memory isn't completely in the dumper I can
recall exactly what
they guys who designed and built the tranny called for and it was 30W,
period. I believe
it was non-detergent, too, but I'm less clear about that part. Oh, and
I drove that for 10
years with no problems EXCEPT when, later in its life, I briefly went
to 5W50 oil and the darn thing refused to stay in OD.
> Now, maybe the later geniuses who drove the British motorcar industry into
>the ground decided to recommend multi-grade did the correct research to back
>up that change, but I'll go with, as you said, what the guys who designed and
>built it recommended.
>
> Jay Donoghue
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