View Full Version : Correct gearbox fluid for TR's???

04-04-2010, 10:10 AM
I just topped up my TR3 trans(actually a TR6 trans) with 80/90 gear oil. I just read that our cars should use GL4 not GL5 or 80/90(contains GL5)as GL5 is corrosive to the brass and copper metals in our gearboxes! Is this true? Should I drain my trans and fill with GL4?

04-04-2010, 10:32 AM
There is at least some truth to it, IMO. I would check the oil that you used, and if it is not also rated MT-1 then replace it fairly soon.

The problem is a particular "active" additive, which is not found in all GL-5 oils.

Geo Hahn
04-04-2010, 10:41 AM
Many opinions & choices, some use motor oil (I use straight 30W in the TR4 w/OD), some use synthetic (I use Redline in the TR3A) and some use gear oil.

You can still get gear oil in GL4 though you may have to look for it at one of the independents on smaller chains.

I use GL4 in the diffs though I do not really know if GL5 would be a problem there.

Now excure me, I running out to the garage to look at the labels on stuff.

04-04-2010, 01:43 PM
https://www.britishcarforum.com/bcforum/u..._oil#Post658087 (https://www.britishcarforum.com/bcforum/ubbthreads.php/ubb/showflat/Number/658087/Searchpage/2/Main/66450/Words/gear+box+oil/Search/true/Re_gear_box_oil#Post658087)

This is the tread that I started not too long ago on the same subject.