Jaguar Mark X / 420 (EU)

Automatic transmission fluid capacity & service interval

Jaguar Mark X / 420 (EU) automatic transmission fluid capacity ranges from 8,5 to 9,5 liters. Service intervals include checks at 2000, 4500, and 5000 km, and changes at 16000 km. The data covers 3 configurations.

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

TypeSpecifications
420G (1966-1970)
  • Use: Normal
  • Capacity 9,1 liter
  • Check 5000 km
Mark X 4.2 (1964-1966)
  • Use: Normal
  • Capacity 9,5 liter (Dry fill)
  • Check 4500 km
Mark X 3.8 (1961-1965)
  • Use: Normal
  • Capacity 8,5 liter (Dry fill)
  • Check 2000 km
  • Change 16000 km

Additional Notes

  • The Mark X 4.2 (1964-1966) carries the largest automatic transmission fluid capacity among the three configurations, with a dry fill of 9.5 liters, indicating a full overhaul or initial build fill rather than a routine service top-up.
  • The Mark X 3.8 (1961-1965) has a dry fill capacity of 8.5 liters, which similarly represents a complete drain and refill from an empty state, as opposed to a partial service quantity.
  • The 420G (1966-1970) lists a capacity of 9.1 liters without a dry fill designation, which suggests the figure may reflect a standard service fill rather than a full overhaul quantity.
  • A change interval of 16,000 km is specified for the Mark X 3.8 under normal use conditions, making it the only configuration among the three to include an explicit fluid replacement interval.
  • The Mark X 3.8 also carries the most frequent check interval at 2,000 km under normal use, compared to 4,500 km for the Mark X 4.2 and 5,000 km for the 420G.
  • The 420G has the longest check interval at 5,000 km under normal use conditions, a figure roughly 2.5 times greater than the 2,000 km check interval assigned to the earlier Mark X 3.8.
  • All three configurations are designated under normal use conditions, meaning none of the listed capacities or intervals are tied to severe-duty operating parameters.
  • The overlap period of 1964-1965 saw both the Mark X 3.8 and Mark X 4.2 in production simultaneously, with the 4.2 requiring 1.0 liter more fluid on a dry fill basis than the 3.8.

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