The Volkswagen transmission and differential are combined in a single case, and lubricated by a common oil. The differential gears are of the hypoid (technically, a special type of skew bevel gearing) variety. Extreme-pressure hypoid gear lubricants must be used because of the high tooth pressures and high rubbing velocities encountered in this type of gearing. Care must be taken to see that straight mineral oil is not used in the Volkswagen transaxle assembly. Such a lubricant would lead to metal-to-metal contact, scoring, galling, and seizure of the gear teeth.
In the Volkswagen transaxle unit, use only good quality SAE 90 hypoid oil all year. In countries with arctic climates, the thinner SAE 80 hypoid oil may be used.
Because hypoid oil can cause corrosion and premature hardening of the main driveshaft oil seal in a car that is stored for a long period, drain the transaxle fluid and refill with an anti-corrosion oil before storing a car for the winter.Automatic Transaxle
This procedure covers both the automatic stick-shift and fully automatic transaxles.
Automatic Transmission Fluid (ATF), such as Dexron® should be used in both of the automatic transaxles. Unlike the manual transaxles, the transmission case and differential case do not use separate fluid reservoirs. Therefore, when the differential is drained, the entire transaxle is drained.
The oil level is checked by removing the 17mm socket head plug located on the driver's side of the transaxle. The oil level should be even with the hole when the vehicle is level. Check it with your finger.
Top up as necessary with SAE 90 gear oil.Automatic Stick Shift Transaxle
The automatic Stick Shift transaxle is checked by means of a dipstick. The oil level should be between two marks at the bottom of the stick. The engine should be warm when the transmission oil level is checked. Top up as necessary with DEXRON®.
The engine must be turned OFF when checking the transaxle oil level.TYPES 2 AND 3
Automatic transaxles are checked in the same manner as Automatic Stick Shift transaxles, except that the engine should be running at an idle, transaxle in Neutral, and parking brake firmly applied. Top up as necessary with DEXRON® through the transaxle dipstick tube located above the distributor (Type 2) or above the air manifold pipes (Type 3). The difference between the two marks on the dipstick is less than one pint. On all Type 2 models and on Squareback Type 3 models, the dipstick is accessible through the hatch in the luggage compartment. On Fastback Type 3 models, the dipstick is reached through the rear engine lid.
DRAIN & REFILL
The oil in the transaxle unit should be changed approximately every 30,000 miles. As with the engine oil, the transaxle lubricant should be changed only after it has reached operating temperature and carries in suspension the maximum quantity of unwanted particles of dirt and other matter. When draining the transaxle oil, both magnetic drain plugs should be removed and cleaned. Because the magnetic tips of the drain plugs are little larger than a 1 / 4 in., they can hold only a limited quantity of iron-based particles. If the oil is drained while the rear end is in an unloaded condition, it is possible that some oil will remain in the half axles. This may change the refill requirement slightly. However, the oil can be drained and renewed regardless of whether the rear end is loaded or unloaded.
There is one very important point of caution in refilling the Volkswagen transaxle unit with oil: if the oil has been put in too quickly it may overflow from the filler hole and give the impression that the unit has been filled when, in fact, it has not. The Volkswagenwerke, therefore, suggests that it is good practice to pour in two or three pints, wait a few minutes, and then pour the rest in.Automatic Transaxle
On automatic models, draining the transaxle oil requires removing, cleaning, and replacing the transaxle oil pan. The refill capacity of each model is given in the Capacities and Pressures Chart.