Rolls-Royce 20/25/30 HP

Manual transmission fluid capacity & service interval

Rolls-Royce 20/25/30 HP manual transmission fluid capacity ranges from 1,14 to 2,56 liters. Service intervals require a change every 16000 km. The data covers 4 configurations.

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

TypeSpecifications
25/30 HP (1936-1938)
  • Use: Normal
  • Capacity 2,56 liter
  • Change 16000 km
  • Code: 4/1
20/25 HP, GKC1-22 -> (1934-1937)
  • Use: Normal
  • Capacity 2,56 liter (Chassis GKT 1- 22 ->)
  • Capacity 1,14 liter (Chassis <- GKT 1- 22)
  • Change 16000 km
  • Code: 4/1
20/25 HP, <- GKC1-22 (1929-1934)
  • Use: Normal
  • Capacity 2,56 liter (Chassis GKT 1- 22 ->)
  • Capacity 1,14 liter (Chassis <- GKT 1- 22)
  • Change 16000 km
  • Code: 4/1
20HP (1922-1925)
  • Use: Normal
  • Capacity 1,14 liter
  • Change 16000 km
  • Code: 3/1

Additional Notes

  • The Rolls-Royce 20/25/30 HP manual transmission fluid change interval is 16,000 km across all configurations covered in the specifications, applied under normal use conditions.
  • The 20 HP (1922-1925) carries a single manual transmission fluid capacity of 1.14 liters, with no chassis-based split in the specifications.
  • The 25/30 HP (1936-1938) carries a single manual transmission fluid capacity of 2.56 liters, reflecting the larger drivetrain of the later model.
  • The 20/25 HP specifications introduce a chassis-number-based capacity split, where units from chassis GKT 1-22 onward take 2.56 liters and units before that chassis number take 1.14 liters.
  • The 1.14-liter figure associated with pre-GKT 1-22 chassis in the 20/25 HP rows matches the single capacity listed for the earlier 20 HP, suggesting a shared transmission unit in the earlier production range.
  • The 20/25 HP specifications are divided into two production sub-ranges: chassis up to GKC1-22 covering 1929-1934, and chassis from GKC1-22 onward covering 1934-1937, both sharing identical capacity and interval values.
  • A capacity of 2.56 liters represents a notably larger fluid fill than 1.14 liters, a difference of more than double, which in transmission service terms typically reflects a physically larger gearbox housing or an additional sump section incorporated into later chassis designs.

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