Rear Transaxle and Front Diff

Syncro Transaxle & Diff. Specs

All T25 Transaxle Specs

Speeds and Axle Ratios


Where is that Transaxle code?

Gbox No Position (small)


Nearside tank strap repair and fuel pump

Nside tank strap and pump mount 2

Transmission Lubes

NB. Transmission components. ‘Transaxle’ and ‘Gearbox’ are words used pretty well interchangeably. Transaxle implies the whole unit with its differential and drive shaft output flanges. At the front, ‘Front-diff’ is usually good enough to differentiate this unit from the transaxle at the rear. Although it contains the Viscous Coupling, its doesn’t ring true to hear it called a centre differential or transfer box, although to an extent, that is part of its role. So we’ll call it the Front-diff (erential) here. For a Syncro, the 5-speed gearbox is often referred to as 4+G, as the ‘extra’ low gear is for using off-road, or gelande.

Lubricants (094 5 – Speed Transaxle)

NB. 1 US Quart =~ 0.95 litres

Capacity (total) – 4.5 litres
Capacity (refill) – 4 litres
(Bentley): 4.205 US Quarts (approx. 4 litres)
(Some say Transaxle is 4.5 litres, there being a portion under the diff, held back by a ball-valve, that doesn’t drain, looks like they’re right)

Spec. (Bentley) SAE 80, GL-4 (Not GL-5, due to bronze synchromesh parts)
VAG 80W/90 GL-4

Front Differential (all)

Capacity 1.5 litres

Spec. (VAG) SAE 80, GL-4 or GL-5

(Bentley): 1.605 US Quarts (approx. 1.5 litres) GL-5

Where are the drain plugs

They both have drain plugs and they both have filler plugs, which should, on a level surface, indicate the correct fill level and capacity.

They are 17mm hex socketed (female) drain plugs, fine threaded.


The drain is just behind where the bellhousing bolts to the gearbox main casing facing aft and downward (of course) and the filler/level plug is almost behind the diff-lock mechanism on the RHS, but accessible, just. However, accessing it with the Syncro’s protection rails fitted is a bit awkward, requiring a particular combination of hex keys and attachments ~ take a good looksee before expecting to drain and fill the transaxle during the Cup Final’s half time break – you might start throwing spanners about!

N.B. The transaxle cannot be fully drained whilst installed, due to a small resrvoir behind a one-way valve under the differential casing – maybe up to 0.5 litres is retained there – if the transaxle is out, then the bellhousing can be removed easily to get this out (refitting with new input-shaft oil-seal~always).

Front Diff

The drain plug is where you would expect it (in the bottom of the casing, central) and the filler/level plug is on the LHS, just aft of the driveshaft, in a recess created by the diff’s fins; not too easy to find if theres a lot of mud and gunk in there.

Have a good look at the magnetic drain plugs when they come out, check the swarf and any bits (colour and particle size tells all) and have a wee poke around as well, maybe tilt the van up a bit and get it warm before draining.

NB. The handbook or manuals might suggest that these lubricants do not need changing, ever. The fact is the main transaxle unit at least, has one or two weaknesses, as well as the possibility of the input shaft oil-seal leaking – long term, this will ensure your box packs up. Checking the level from time to time and topping up is a wise move with these boxes, and a drain and refill when taking ownership with an uncertain history, a precaution that could save a lot of trouble and expense.


PS. I used SX70W90 Semi-synthetic GL-5 Oil in the front diff, a Comma style cheapie (for a synthetic), but probably as good or better than many non-synths.

If you want to use a top fully synthetic oil in the transaxle yet retain a good gearchange, Redline MTL is the one to go for.

MTL – Manual Transmission Lubricant, is a 75W/80W GL-4 gear oil. It is used in place of the normal gear oil, providing excellent gear protection, it has a superb coefficient of friction, making for easier gear shifting, especially when the box is cold.

But its not cheap:

Manual Transmission Lubricant – Synthetic

MT90 is their 90W GL-5 full synthetic suitable for the front diff (if you can afford it)

Avalaible from C & R Enterprises or Redline themselves