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Should Tranny Oil be changed?

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TR4

TR4

Jedi Warrior
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The previous owner told me he put 90W oil in the TR4 Tranny. Should I change it to 20W-50W as my manual calls for or is the 90W OK in there.
 
Is it a non-overdrive?

I just put a TR4 trans (non-OD) in my TR3 and it is calling for 90W GL4. I would make sure they put in GL4 and not GL5.
 
If you can't find GL-4 oil locally, try to Google GL-4 and find who has it. It's scarce because GL-5 is claimed by the oil companies to supercede GL-4. But GL-5 has additives that can damage a gearbox which has bronze or brass parts in it - like all TR gear-boxes have. That's why you should look for GL-4.

Or put in 20W50 which has none of these bad additives. I have driven my 1958 TR3A with gearbox/overdrive for 98,000 miles and find a bit of yellow fines when I change the oil every 3000 to 5000 miles. I have been using Valvoline 20W50 Racing Grade since 1990. I rebuilt it completely in 2004 after I broke a bronze top-hat bushing in it by roll starting the car in gear. Don't do that - especially when rolling backwards in reverse.
 
It is non-overdrive but there will be no way to make sure they did not use GL5 so I will change it out. I appreciate your advice.

Phil
 
Or you might consider a RedLine synthetic. That is what I use in my non-OD 'box.

Many prior threads on synthetic vs motor oil vs gear lube.
 
Or Valvoline Non-Detergent 30 wt. That is what I run in my tranny (with J-type overdrive).
 
I'll vote for Bill's ND-30W as the most "period correct" and least chancy.
 
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