Transmission oil change, which oils

[Gary.]

Time for a transmission oil change, given the unknown history of the vehicle and I clocked a small weep off the rear diff, it seemed wise.

Never done this before, but have read differing opinions about the oil choice, specifically between front and rear.

So the rear gearbox & differential are the same thing and I've read 75W90 GL-4 is suitable. Will this be OK?

For the front, do I use the same, or SAE80 GL-4, whatever that is?

Any advice gratefully received.

[bene]

Hey Gary,
Info you need is in the syncro wiki... this link should work.
http://www.syncronauts.org.uk/syncro-te ... front-diff

But basically GL 4 in both or GL4 in gearbox, GL 5 in front diff.
cheers

[Gary.]

That's where I got the info from last night. I'll just stick with a good GL-4 for now.

[Aidan]

Gary
hi GL4 correct for gearbox and fine in front diff
75w/90 fully synth that meets VW 501.50, MIL2105 etc... in a perfect world, at the moment I'm using UK blend from SMITH and Allan in Co Durham off ebay I have checked with their technical that it's correct, there's plenty of Manoil from Germany about too
Molyslip GM6RA for the synchro rings helps every couple of oil changes on the gearbox just add one 65ml shot
For Weddle HD gearsets recommendation now is to goto 75w/140 as the duty cycle especially in 4th even with the oil plates is short and temps can rise higher

[Gary.]

Thanks, I'll be changing today. Picked up the following from local car parts place:

Comma MVMTF 75W-90 API GL-4 fully synthetic

Will use it front and rear.

For a novice mechanic like me, this little tool will make the drain plugs easier to access:

[R0B]

Make sure the filler nut comes loose before removing the drain nut.

[Gary.]

Great advice ROB, I read that somewhere before and did exactly that. Just got in from a whole day under the truck, quite a learning experience!

So, advice to others attempting the same with numpty grade knowledge...

• Make sure you have the tools to access all plugs.
• Have a good bucket or pan for collection of silvery stuff that comes out!

Tackled the rear first, the filler plug is a sod as you need a knuckle and extension to get the angle past the syncro underbody protection bars. I cleaned out the 17mm recess with a small screwdriver so I could ensure a good bite from plug tool. Came out really easy. The complete sod was the main drain plug, I had assumed easy access (you know what they say about assumption!), but the sump protector (late type in my case), completely obscured access for allen key / plug tool etc. I tried the using a 10mm threaded nut on bolt, but it kept undoing, rather than the plug. So eventually managed to put a jack under the protection plate and get the plug tool in. Pic here with double-nut arrangement:



The rear plug looked like a christmas decoration, which I guess means it was doing its job! Refilling was a little slow. I used a standard length of hose (clean spiders out first!), with a hoselock connection to take an ex-kitchen funnel [she never used it anyway!]. Handy having a doka as there is a convenient bed for the tools! Managed to get 4 litres in, as suggested on the syncronauts website.



The front was a piece of psss. Easy access, and took 1.5 litres of oil.

Thanks for the guidance. All made easier with my new mini-pit, with carpet!:



*no idea why the pics are sidewards, all good on my pc?*-

[max and caddy]

A m10 studding joiner makes a cheap plug removal tool...Aidan , smith and Allen seem to list several options on the oil...I think I have a semi synthetic option in my SIKA...what's is your prefered option?

[Aidan]

as I said the fully synth 75w/90 ; that is comparable to the G50 VW used back then and meets the MIL2105 spec and is GL4 compatible as well as GL5

[max and caddy]

I'm sure I recall a video for the then new Passat stating that G50 was a new oil developed specific for the 02A transmissions....that would be 1990.. anyway if it meets the spec it's ok...I'm currently using smith and Allen oils but can't recall which one is in which box...I have tried several oils in the SIKA and it still has a very poor shift compared to the van....despite both being fitted with the same new baulk rings....I have given up on it now and just going to run it till it breaks.

[Colm5928]

Gary, I have to perform this task at the weekend and thanks for the heads up on the various challenges/problems associated. Just a couple of questions on the gear changing, with the old oil was gear selection difficult? has the new oil made much of a difference on ease of gear selection when cold and hot?

[Gary.]

There was a subtle difference, though I can't be sure that's down to the oil alone. Going into 3rd (or is that 2nd on a syncro?) was always a little sticky.
I also cleaned up the linkages and gave everything a big grease pasting, so can't really be sure. For me it was just peace of mind.