Syncro Gearbox and dif oil
Toomanytoys But front diff can take GL5 80 or 75w90 oil.. so put in a good brand and spend as much as you want on it... You dont need a huge amount..
From Syncro web pages: 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 being incompatible with some of the GL-5 additive package; this is now argued against by some, especially for GL-5 synnthetic oils) 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.
Transaxle 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.
Oils
I used SX70W90 Semi-synthetic GL-5 Oil in both, a Comma style cheapie (for a synthetic), but probably as good or better than many non-synths.
Aidan
please can the reference to Redline MT90 be pulled from the WIKI, I do not recommend this oil at all, every box I've known that has had it has had issues, and there is a lot of evidence from the states of excessive wear with this product, Daryl at AA transaxles has been looking at this problem and now he no longer recommends it and on the Vanagon forums it's been spread about that it's not good - unfortunatly the UK importer is targeting the T3 market on ebay, based on old recommendations
the carplan 75w/90 gl4/gl5 is what i use now that the Fuchs is no longer readily available, if you want to spend a lot of dosh then use Millers, and if you want to spend a fortune then use the SWEPCO, but personally I go with the £20 stuff regularly changed and from what I'm seeing on wear after 5 years that advice stands
MTL - Manual Transmission Lubricant, is a 75W/80W GL-4 gear oil (frequently usde in Golf GTi gearboxes to improve gearchange). It is used in place of the normal gear oil, providing excellent gear protection; it has a coefficient of friction dsigned for making easier gear shifting, especially when the box is cold. Avalaible from C & R Enterprises or Redline themselves in UK. Its is possibly a bit light viscosity for Syncros (see Redline MT90)
