jimi wrote: ↑17/05/18 1:47
I've had Castrol Syntrax 75w90 Universal in my MK1 gearbox for well over 10 years (13 to be accurate) never had the slightest problem and the gear changes are as slick as when I got the car, maybe I've been lucky, maybe not, as I said there's a lot of conflicting info and stories out there.
Well lucky from the point of view you chose Syntrax like me, but not lucky that that particular oil doesn't eat your gearbox because its not eating mine either.
Its going to be next to impossible to do the research if it takes 8 years to stuff the gearbox, by that time the car is usually bought and sold and nobody will know the service history, what oil was used let alone if the gearbox has been rebuilt or not.
If your worried I suggest just go for a GL-4 and change it every few years because NOT changing it does as much damage as the oil eating it anyway.
The oil should look as clean when it comes out as when it went in, in fact as I have posted before I have REUSED the oil in an older car gearbox. If you store it for 6 month, all the crap settles out and sticks to the bottom of the container so if your pour it off carefully and discard whats in the bottom its still a whole lot better than an oil thats been in a gearbox for 20 years or just use it as a "Flush" to get rid of the non sythetic.