Andrew,
Either HD 30, 20w-50, or Red Line MTL will work. MT-90 is physically
thicker and I wouldn't use it except under racing conditions where the
heat will thin it enough for the pump to pump it and for it bleed out
when the OD is switched off.
If you use motor oil, I recommend you change it every 20,000 miles. I
did this on my '65 for the first 150,000 on that OD, and I will change
Red Line every 50,000 miles. So, either method will provide very good
longevity, I just like the smoother shifting with the MTL too much to go
back to motor oil.
The "stiff shifting" on a new box is simply because MOTOR OIL IS TOO
SLIPPERY FOR THE SYNCROS, and they have to be forced against the gears
much harder to bite and stop their spinning. After you have worn them
down a bit there is more surface area to grab with, so, change your oil
after the first 5000 miles to get rid of all the break-in detritus. Red
Line gives the sycros the proper bite with its additive package.
Remember that when these cars were built the only choices for the tranny
were hypoid gear oil (very thick) and ND motor oil. We have more
options in the year 2000, including far superior motor oil.
(On a related note, I use MT-90 in my Vanagon, which is a notoriously
stiff shifter, and it reduced the shifting effort to an amazing degree,
especially on winter mornings when I was sure I was going to break the
shifter off trying to get into first gear.)
To summarize, my reason for using MTL is not for any benefit in
particular for the OD, but for the shifting (i.e., syncros), and
superior lubrication over time that only a synthetic can provide. I
just don't want to harm the OD, and after 50,000 miles my inspection of
the friction linings showed that I have not.
Stay tuned, I'll report on my 100,000 mile Red Line MTL experience with
both the D and LH type overdrives, but it probably won't be for about 10
years! And who knows, maybe I'll salvage that '68 parts car and start
racing it--then I'll test my MT-90 theory!
"Andrew B. Lundgren" wrote:
>
> Yeah, I'm afraid I am going to go with the list, neighbor,
> manufacturer, manuals and guy who rebuilt my tranny. (My neighbor
> tried the MT-90 in his, he said it took about 3 miles @ 35-40mph to
> dis-enguage after he flipped the switch. He has since gone to 20W-50
> and is very happy)
>
> I agree with your thoughts on using the HD over the ND. Someone on the
> list (IIRC) suggested the ND, but my other tranny with the HD shifted
> beautifully, I am hoping that a little breaking it, with the detergent
> will bring this one inline with that one.
>
> The oil bottle recommends using ND for old engines that burn/leak a lot
> of oil or for non-critical gas engines (whatever that means.) I guess
> the thinking is the engine is shot anyway and this stuff is cheaper to
> keep dumping in.
>
> On Wed, 19 Jul 2000 15:15:27 -0700, Stuart MacMillan wrote:
>
> >I see I have failed to convince you of the superiority of Red Line MTL,
> >Bill and I can argue this one at the ABFM on Saturday, but I know there
> >is no point in doing that. If I had a spare OD tranny lying around
> >(that I had personally rebuilt) I'd give it to him with MT-90 in it to
> >try in his next race!
> >
> >If you choose to run motor oil for some crazy reason in your daily
> >driver, run the HD type. Non-detergent oils are for purposes other than
> >putting in engines (or transmissions, I feel), like in oil cans for
> >lubricating your bike chain, or you could use ND 20 in your SU
> >dashpots. I have used ND 30 oil in newly rebuilt engines for the first
> >500 miles, its inferior lubrication qualities are supposed to help the
> >rings seat, but I don't know that it really makes any difference.
> >
> >The detergent in HD oils is for suspending the particles generated by
> >combustion and preventing the formation of sludge in engines. BUT, oils
> >that meet the current SAE standards are not only all HD, but have
> >additive packages for anti foaming, corrosion resistance, and pressure
> >breakdown prevention that the basic ND oils may not have. The detergent
> >won't hurt anything in the tranny, and you are getting a better additive
> >package with a modern HD oil.
> >
> >I'll bet you will get easier shifting too, but not as easy as with Red
> >Line MTL! ;-)
> >
> >--
> >Stuart MacMillan
> >Seattle
> >
> >'84 Vanagon Westfalia
> >'65 MGB (Driven since 1969)
> >'74 MGB GT (Restoring)
> >
> >Assisting on Restoration:
> >'72 MGB GT (Daughter's)
> >'64 MGB (Son's)
> >
> >Parts cars:
> >'68 & '73 MGB, '67 MGB GT
> >
>
> Andrew Lundgren
> Lundgren@iname.com
> http://www.itwest.net/~lundgren
--
Stuart MacMillan
Seattle
'84 Vanagon Westfalia
'65 MGB (Driven since 1969)
'74 MGB GT (Restoring)
Assisting on Restoration:
'72 MGB GT (Daughter's)
'64 MGB (Son's)
Parts cars:
'68 & '73 MGB, '67 MGB GT
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