Austin-Healey 100

Differential fluid capacity & service interval

Austin-Healey 100 differential fluid capacity ranges from 1,6 to 1,7 liters. Service intervals occur every 6000 miles or 9600 km. The data covers 4 configurations.

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

TypeSpecifications
  • 100/6, BN4 / BN6 (1957-1959)
  • Rear
  • Use: Normal
  • Capacity 1,7 liter
  • Change 6000 miles/ 9600 km
  • 100/6, BN4 (1956-1957)
  • Rear
  • Use: Normal
  • Capacity 1,7 liter
  • Change 6000 miles/ 9600 km
  • 100/4, BN2 (1955-1956)
  • Rear
  • Use: Normal
  • Capacity 1,6 liter
  • Change 6000 miles/ 9600 km
  • 100/4, BN1 (1953-1955)
  • Rear
  • Use: Normal
  • Capacity 1,6 liter
  • Change 6000 miles/ 9600 km

Additional Notes

  • The Austin-Healey 100 rear differential carries 1.6 liters of fluid across both BN1 and BN2 variants produced from 1953-1956, reflecting a consistent housing size between those two early four-cylinder configurations.
  • With the introduction of the six-cylinder BN4 in 1956, the rear differential capacity increased to 1.7 liters, a figure that carried forward through the BN4 and BN6 variants covering 1957-1959.
  • The 0.1-liter difference between the four-cylinder and six-cylinder differential capacities points to a slightly larger rear axle housing adopted alongside the engine upgrade, rather than a shared carry-over unit.
  • All four configurations share an identical service interval of 6,000 miles or 9,600 km under normal use conditions, applied uniformly across the full 1953-1959 production span covered by these specifications.
  • A 6,000-mile change interval was a relatively frequent schedule by mid-century standards, consistent with the lubrication technology and gear oil formulations typical of that era rather than the extended drain intervals associated with modern synthetic fluids.
  • The normal use condition applies to all listed configurations without variation, meaning the 6,000-mile interval and the stated capacities are tied specifically to standard operating circumstances across every BN1, BN2, BN4, and BN6 variant.

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