Really easy question this one. Going to topup the gearbox oil, which oil should I use? Manual says SAE90, but Halfords don't have this (I think it's an old number system?) It's a 1978 type 2 1600 converted by Devon.
Whatever you choose it must be an API GL4 spec like the Halfords mineral gear oil above. A monograde such as SAE90 will do, a multigrade such as SAE 80W-90 is better and a Synthetic SAE 75W-90 is better still. For the few extra quid compared to a mineral oil I’d use a synthetic such as Castrol Syntrans Multivehicle 75W-90.
As above, make sure it's GL-4, NOT GL-5. There's all sorts of debate about the suitability of GL-5 for gearboxes in VW air-cooled vehicles, so you should just stick to GL-4. Have a look here for a summary: http://www.ratwell.com/technical/GearOil.html#gl5
I have to Pee on your bonfire @baybirmingham ... I did some research into the whole GL4/GL5 debate, and GL5 is actually better... The whole corrosive issue, is and was never going to be an issue, as the GL5 oil can only become corrosive if the oil temperature exceeds 270°F... And lets face it, if your box oil hits that temp, then you have a serious problem!! And there is a new version of GL5 available that has a MT1 code attached to it, that means that any corrosive substances have been removed And GL5 is better in a bus box, as it is a higher pressure rating, so your box will last longer
I confess next time around I'm going to fill mine full of semi-synth. The "traditional" stuff just makes the 'box so baulky when it's cold.
I have to say, the gearbox on my van is fine, cold or hot. So no real issues there. Just wnted to make sure it was looked after before I run it into France!
That's interesting, it's not peeing on my bonfire, I'm always willing to learn.... I did a lot of reading around about the GL-4 vs GL-5 debate when I changed the oil in my gearbox. I will bear this in mind next time I change the oil in the box.
I’ve done a bit of research into the GL-4/GL-5 debate too. Particularly the suitability for use in manual transmissions with synchroniser rings. It is difficult to know whether a GL-5/MT-1 is suitable for a transaxle or not; you’re unlikely to get oil or transmission manufacturers to confirm it is because no testing has or will take place and of course there would be legal liabilities if things went wrong. What we know is that VW specified a GL-4 lubricant for the manual transmission. When gears slide against each other there is a very high load and localised high temperature that the EP component within the oil film has to resist, you’d think that oil with the highest resistance to extreme pressure would be preferable (and VW recommended a GL-5 for the final drive on automatics). Unfortunately it’s not that simple with the transaxle, there must be good EP protection but the synchroniser rings must be able to cut through the oil film to synchronise the gear speed for engagement and the EP additive must be non-corrosive to yellow metal. And this is where it gets really difficult because not all oils have the same base stock or contain the same additive pack. I doubt if there is any evidence that a transmission originally intended to be lubricated with GL-4 oil will last longer with a GL-5, but if it did have a longer life it could also have been more difficult to use with a slow and bulky gear-change. ‘Better’ for me is a smoother gear-change and the chances of this are higher with a Synthetic multigrade gear oil to GL-4 rather than GL-5 specifications - I’ll continue to use Castrol Syntrans Multivehicle 75W-90 because it is readily available and relatively cheap, but there are several very good alternatives. What oil do you use Paul?
Yes, noticeably easier and smoother, especially when cold in a 5-speed box in my V8 MGB and in the six-rib in my 2.0l Bay. About 13 years in the MG and 2½ in the Bay.
