Steyr S23

Manual transmission fluid capacity & service interval

Steyr S23 manual transmission fluid has a capacity range of 8 to 15 liters. Service intervals include checks every 20000 km and changes every 40000 km or 12 months. The data covers 5 configurations.

The configuration chart below lists fill volumes and service intervals for each engine and trim variant.

TypeSpecifications
15S23 4x4 (1988-1996)
  • Use: Normal
  • Capacity 8,5 liter
  • Check 20000 km
  • Change 40000 km/ 12 months
  • Code: ZF 16S-109 16/1
15S23 4x4 (1988-1996)
  • Use: Normal
  • Capacity 8 liter
  • Check 20000 km
  • Change 40000 km/ 12 months
  • Code: ZF 9S-109 9/1
15S23 4x4 (1988-1996)
  • Use: Normal
  • Capacity 13 liter
  • Check 20000 km
  • Change 40000 km/ 12 months
  • Code: ZF AK/S6-65 + GV 80, AK/S6-80 6/1
15S23 4x4 (1988-1996)
  • Use: Normal
  • Capacity 11 liter
  • Check 20000 km
  • Change 40000 km/ 12 months
  • Code: ZF AK/S6-65 6/1
15S23 4x4 (1988-1996)
  • Use: Normal
  • Capacity 15 liter
  • Check 20000 km
  • Change 40000 km/ 12 months
  • Code: ZF AK/S6-80 + GV 80 6/1

Additional Notes

  • The Steyr S23 in the 15S23 4x4 configuration lists five distinct manual transmission fluid capacities across the 1988-1996 model range: 8, 8.5, 11, 13, and 15 liters. A spread of this width across a single transmission type typically reflects differences between individual gearbox assemblies, axle units, or transfer case components that are each serviced separately rather than as a combined fill.
  • The 15-liter capacity figure is the largest among the listed values and is consistent with a full overhaul or dry-fill scenario, where all fluid has been drained from a large multi-component drivetrain assembly and the system requires a complete refill from empty.
  • The 8-liter and 8.5-liter capacities are the smallest in the set and are more consistent with a standard service fill for a single gearbox unit, representing the volume needed to bring fluid up to the correct operating level during routine maintenance.
  • All five capacity entries share identical check and change intervals under normal use conditions. The fluid level is checked every 20,000 km, and a full fluid change is performed every 40,000 km or every 12 months, whichever comes first.
  • The 12-month time limit paired with the 40,000 km change interval means a fluid change is due when either threshold is reached first. For vehicles covering lower annual mileage, the calendar interval would trigger the service before the distance threshold is met.
  • The check interval of 20,000 km falls at exactly half the change interval of 40,000 km, placing one fluid level inspection between each scheduled change. A mid-cycle check at 20,000 km allows for detection of fluid loss or contamination before the next full service.

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