Diff oil - what's preferred?

[GreatCrestedNewt]

I'm about to buy oil for the rear diff of my T4 Syncro but have both diff and the gearbox of a T25 Syncro to replenish shortly so am thinking that I might as well buy at least 5 litres while I'm at it. I've got a tub of mineral EP90 in the shed but figure that a part or fully synthetic 75W90 GL-5 would be better suited. Any recommendations or thoughts on this would be appreciated.

[v-lux]

Not sure for T4 syncro gearbox or diff oil...

But oil for gearbox in a T3 must be GL4 as it eats away a brass synchro ring thing-a-me-bob.....or something....
GL5 is ok in the front diff though.

But im sure Aidan will be along to give some professional advice soon enough...

[GreatCrestedNewt]

Just ordered FUCHS TITAN SYN GEAR OIL 75W-90 from GSF. I going to use that for all my T25 & T4 drivetrain needs.

[Aidan]

cool for the T3
I don't know about the T4 I am afraid, modern machinery that, too complex for me

[xpress]

ok. a bit confused. is mineral better or semi synth or full synth 75w90 in gl4 spec and why? also is a release bearing the Spigot bearing? and can you drop the gearbox without dropping the engine?

[syncropaddy]

[syncropaddy]

also is a release bearing the Spigot bearing? and can you drop the gearbox without dropping the engine?

No. The release bearing is part of the clutch release mechanism and the spigot bearing is in the end of the crankshaft to support the input shaft. Yes you can drop the 'box without dropping the engine.

[syncrosimon]

I suspect vw were just talking about not changing the oil when the vehicles were current models. I remember my dad had a 1986 Caravelle DG, the gearbox went on that in 1991, after about 100,000 miles. The ex VW mechanic that replaced the box stated that in his opinion the failure was caused by a lack of lubrication. The vehicle had been fully dealer serviced to that point and because of VW's policy of forget about the gearbox the low level was not detected until after the gearbox was destroyed.

Fair enough why change the oil on a young vehicle, but these old girls need fresh and new oil, if only to eliminate whatever the previous owner put in and get the levels right.

Looking at what vw wrote in a manual in the late 70's does not mean anything now.

If you did not put the oil in, then change it so that you know it is right.

[syncropaddy]

I suspect vw were just talking about not changing the oil when the vehicles were current models. I remember my dad had a 1986 Caravelle DG, the gearbox went on that in 1991, after about 100,000 miles. The ex VW mechanic that replaced the box stated that in his opinion the failure was caused by a lack of lubrication. The vehicle had been fully dealer serviced to that point and because of VW's policy of forget about the gearbox the low level was not detected until after the gearbox was destroyed.

Well if there was lack of lubrication that caused the failure then the oil must have leaked out, where else would it go .......... but its only an opinion! I fail to see how VW's 'policy of forget about the gearbox' is to blame for a leak not being detected. There is a Syncro on e bay at the moment (http://www.ebay.co.uk/itm/280744084629? ... 1423.l2649" onclick="window.open(this.href);return false;) that has a duff box after 103,000 miles. I drove this Syncro (and even posted here about it) and the gearbox is knackered. Its owner said at the time that its due to abuse - plain and simple.

Castrol claim that their Syntrans products last for 400,000 miles and VW say dont change oils ...... its a no brainer really

[Simon Baxter]

I think here, the gearbox was "filled for life", however VW only designed the vans to last 8-10 years, that's a lifetime.
Filled for life really means filled for 8-10 years.

In honesty Andrew, I'm sure I've said this before, you don't see the stuff that we drain on a weekly basis, and if you did you would change your gearbox oil.

[lhd]

I used Castrol (exact VW specs) on my T25 2wd and never had any problems until I changed to the Fusch from GSF (slightly wider range), it seemed ok in the summer but as soon as winter arrived the change got considerably more difficult in first and second.
Now this could be a coincidence, but personally I'm not convinced as this seemed too much of a coincidence for my liking.

The Castrol was bought from Halfrauds and did cost about £25 for a fill due to only being available in litre bottles, but I'm sure if I had looked about I could have found it cheaper.
Obviously I'm no expert and this is from personal experience only.
Rob.

[syncropaddy]

..... VW only designed the vans to last 8-10 years.....

Who said?

In honesty Andrew, I'm sure I've said this before, you don't see the stuff that we drain on a weekly basis, and if you did you would change your gearbox oil.

On all of my vehicles I change brake fluids regularly because brake fluids are hydroscopic and to do so is recommended by the fluid and vehicle manufacturers, on my automatics, I change my AT fluids as recommended by the fluid and transmission manufacturers, I change my engine oils and filters as recommended by the fluid and vehicle manufacturers. So why should I go against the fluid and transmission manufacturers when it comes to manual gearboxes?
Unlike a lot of posters on this forum, I've been around a long time, I have driven huge mileages and owned many new cars and driven them hard and long and always serviced them to manufacturers requirements as laid out in their service schedules and never once have I had a vehicle that has had gearbox issues or a gearbox oil change. I'm sure we have vehicle examples from both sides of the argument - I know I have but why should the advice of the fluid and transmission manufacturers be ignored? It doesn't make sense.

[jebiga41]

Unlike a lot of posters on this forum, I've been around a long time, I have driven huge mileages and owned many new cars and driven them hard and long and always serviced them to manufacturers requirements as laid out in their service schedules and never once have I had a vehicle that has had gearbox issues or a gearbox oil change.

Never say never
More here https://club8090.co.uk/forum/viewtopic.p ... 1&start=15" onclick="window.open(this.href);return false;

[syncropaddy]

Unlike a lot of posters on this forum, I've been around a long time, I have driven huge mileages and owned many new cars and driven them hard and long and always serviced them to manufacturers requirements as laid out in their service schedules and never once have I had a vehicle that has had gearbox issues or a gearbox oil change.

Never say never
More here https://club8090.co.uk/forum/viewtopic.p ... 1&start=15" onclick="window.open(this.href);return false;

[xpress]

today several pros said that 75 90 may be too thin especially for an older box and you need thicker to take up the slack. even original workshop manual states 80 straight mineral formulation. I am going for 80 90 gl4. light changes may be desirable but do you want to wear your box out quicker as a result?