When in doubt use rip off oem gearbox oil , they want £24.90 1L for mine , no thank you !
Having read the article there's a few problems with it , the do not use GL5 under any circumstances is not true and out of date .
GL4 does have less EP additives namely sulphur that can attack yellow metals on the synchromeshes , but it's the level of sulphur that's important , it still has sulphur that's why it pen and inks .
The level of sulphur is the case for certain GL5's as some are aimed at manual transmission some with more EP additives at diffs .
Ever seen a gearbox oil marked up as a GL4 and 5 or a GL4+ ?
Classic example is my original spec 501.50 also known as G50 or G 005 000 and it is a GL4 75W90 has now been superceded as checked both with a stealer and TPS to be G 052 911 which is a GL5 75W90 also found as oe 75W80 by a couple of manufacturers that have decided that 75W90 is way to thick and quite rightly so , which brings me onto the next subject - viscosity .
Now 75W90 is thick stuff I've 75W90 in the form of Redline MT90 in a Jap petrol turbo and these Fast n furious cars get thrashed around a track and drifted . As the name suggests but not always the case MT90 is 90 Centistokes at 40°C which is thick , despite the lable saying
- Eliminates notchy shifting
- Designed for manual transmissions and transaxles
- Perfect synchronizer coefficient of friction
- Enables high-speed downshifting
- Excellent shifting even when cold
I've got stiff lower shifts when cold , hot it disappears , classic cold viscosity issue as the previous gearbox oil whatever that was didn't have the issue.
I may try when I get it back on the road the lighter Redline version MTL .
Now why do you need a 75W90 in a road car - you don't , that's why two oe went 75W80 and VW produced G 052 171 a 70W75 for those experiencing poor cold shifting .
So you could even use that.... but don't buy rip off genuine...
