• Hi Guest!
    You can help ensure that British Car Forum (BCF) continues to provide a great place to engage in the British car hobby! If you find BCF a beneficial community, please consider supporting our efforts with a subscription.
    There are some perks with a member upgrade!
    **Upgrade Now**
    (PS: Subscribers don't see this gawd-aweful banner
Tips
Tips

1500 with OD transmission oil recommendations

Share this page

R

recordsj

Jedi Warrior
Offline
I have a 75 MG Midget with a J-type OD transmission that came from a 1500 spitfire. I was wondering if people can respond to what is recommended for the oil for the transmission. Any insight or info on what is best for this setup?
 
Overdrives use the same oil as normal Spitfire transmissions. For temperatures above 30 degrees F use 90 weight Hypoid gear oil. That's what I used in the J-type OD that I put in my '75 Midget 1500 in 1989.

By any chance is your little Midget yellow and black? Does it have slightly damaged rear bumper mounts? Does it still have the plastic suspension bushings I put in, or the oil cooler, or the SK side-draft carb?

Scott (in Oregon)
 
Cool. It's nice to know that someone other than me went to the trouble of putting in an overdrive.

For what it's worth, I had better luck with regular Castrol hypoid gear oil than with synthetic hypoid. The synchros worked better with normal hypoid, so I graunched the gears less.

Scott
 
so where do you pick up some castrol hypoid gear oil? If I remember correctly the oil needs to be GL-4 since GL-5 is harmful to the brass parts in the transmission?
 
The Castrol hypoid gear oil I bought was GL-5 because it was the most commonly available stuff 20 years ago. I never heard that GL-5 was harmful for bronze bushings or synchros (there shouldn't be any brass parts in a transmission). I have a feeling that it was more common in the Seventies than it was in the Eighties when I owned my Midget.

Nowadays most hypoid gear oils are both GL-4 and GL-5 compliant, since the difference is in stress-bearing additives. I see from Googling that some truck guys and some mower guys think that GL-5 degrades synchros, but I have never observed that in Spitfire or Midget transmissions in years of driving. I have a feeling that it is an urban myth. Castrol still makes Hypoy C, which is what I used with good results years ago.

Scott
 
I found GL-4 at a company owned NAPA store. Only place i could find it. After reading the article foxtrapper referred to above, I changed to non-detergent 30 weight. Both worked fine and I could tell no diffenrence.
 
foxtrapper is right. I've been playing with these cars almost 30 years. I've seen everything mentioned in the article. I run straight 30 non detergent only.
 
recordsj said:
so where do you pick up some castrol hypoid gear oil? If I remember correctly the oil needs to be GL-4 since GL-5 is harmful to the brass parts in the transmission?
Click to expand...
FYI, if you specifically want GL-4 gear oil and can't find it locally, TRF sells it.
 
30 weight non-detergent in a Type J... seems to make sense. I've got nothing against it, especially since my Saab 900 transmissions use 10W-30 motor oil without any problems.

I am surprised that QuantumMechanics had problems with 90 weight gear oil, though. I used 90 weight hypoid for two years in my Midget's Type-J without any problems at all. And, as mentioned in the QM article, it is recommended in the Spitfire's owner's handbook.

Scott
 
I use synthetic GL5 75W90 gear oil in my 1500's OD transmission. The gear oil I'm using states that it is compatible with yellow oils, which really isn't a concern in the transmission, more of a concern in the differential.

The Laycock OD is not fussy about the type of oil used. Volvo, who put over 400,000 Laycock ODs in their cars started out recommending motor oil, and later recommened gear oil, and then finally recommended ATF.

There is probably nothing wrong with using 30 wt, but Quantum's reasoning isn't good.
 
Back
Top