How to change (check) AUDI transmission oil

Since you say gear oil I assume that it is a manual transmission. Here are codes and fluid type/capacity
Transmission fluid Capacity 2.0 liters
Transmission code: DYP, ECW, EFG, ERS, FBV, FBX, FBY, EGY, EVR, EZK, FCF Type G51 SAE 75w-90 (synthetic oil)
Transmission codes: DQY, DBZ, DZQ, DZC, EGC, EGF, EKG, EMR, EMS, ENH, ENJ, EBJ, EBP, EBQ, EZH, EWW, FBW, EGR, EBN, EGT, EGX, EGU, EHC, FDS, EHA Type G50 SAE 75w-90 (synthetic oil)

The transmission oil type for Audi A4 MY 2000 with manual gearbox is:
Synthetic oil SAE 75 W 90, part number G 052 145 S2 (1 liter).



Example:
Castrol Syntrax 75W-90 Full synthetic SAE 75W/90, API GL5. manual transmission, transaxle and rear axle lubricant with outstanding extreme pressure, synchroniser and high temperature performance.

Manual gearbox- SAE 75 W 90 Synthetic. Auto Gearbox- VW ATF only available from Audi dealers. Differential SAE 75 W 90 Synthetic.

hi here is a list with the type of engine oil you need also gearbox type as well in case you need that to
Engine
cold climate sae 5w/40 synthetic
moderate climate sae 5w/40 synthetic
hot climate sae 5w/40 synthetic

GearBox Manual
sae 75w/90

gearbox Auto
none stated

hope this helps

Transmision oil for 2001 Audi A4 1.8 l turbo:
Manual gearbox (5 speed):
- Capacity = 2,25 liters
- Specification: Gear oil SAE 75 W 90 (synthetic oil)
Part number G 052 145 S2 (1 liter)
- To check oil level, unscrew oil filler plug placed on the left side of the gearbox in front and near of transmission axle, using an Allen 17 mm key.
- Check oil level with locally manufactured tool, e.g. a piece of angled wire.
- Specification: oil level 7 mm below bottom edge of oil filler hole.
- Install oil filler plug, tightening torque = 25 Nm.
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