Isuzu H series (USA / CAN)

Manual transmission fluid capacity & service interval

Isuzu H series (USA / CAN) manual transmission fluid capacity ranges from 5,5 to 13,8 liters. Service intervals include checks at 7500 miles or 3 months and changes at 400000 miles or 60 months. The data covers 2 configurations.

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

TypeSpecifications
H series (2007-2008)
  • Use: Normal
  • Capacity 13,2 liter (RT8908LL)
  • Capacity 12,3 liter (RT8709)
  • Capacity 9,2 liter (FS5406A, FS6406)
  • Check 7500 miles/ 3 months
H series (2003-2006)
  • Use: Normal
  • Capacity 5,5 liter (FS5205A, FS5205C)
  • Capacity 8,7 liter (FS6305A, FS6305B)
  • Capacity 8,8 liter (FS5406, FSO8406)
  • Capacity 5,9 liter (RT6609)
  • Capacity 11,8 liter (RT8709B)
  • Capacity 13,8 liter (RT8908LL)
  • Check 7500 miles/ 3 months
  • Change 400000 miles/ 60 months

Additional Notes

  • The 2003-2006 Isuzu H series (USA / CAN) manual transmission fluid specifications cover six distinct transmission models, each with its own capacity value, ranging from 5.5 liters in the FS5205A and FS5205C up to 13.8 liters in the RT8908LL.
  • The RT8908LL capacity shifts between model year groups: 13.8 liters is specified for 2003-2006 units, while the 2007-2008 specification lists 13.2 liters for the same transmission designation.
  • The FS5406 appears across both year groups under different naming conventions. For 2003-2006, the FS5406 and FSO8406 share an 8.8-liter capacity, whereas the 2007-2008 group lists the FS5406A alongside the FS6406 at a higher 9.2-liter capacity.
  • The RT6609 and RT8709B are transmission models exclusive to the 2003-2006 specifications, carrying capacities of 5.9 liters and 11.8 liters respectively.
  • For 2003-2006 configurations under normal use conditions, a fluid check interval of every 7,500 miles or 3 months is paired with a change interval of 400,000 miles or 60 months. A 400,000-mile drain interval reflects a heavy-duty commercial service expectation rather than a typical light-vehicle schedule.
  • The 2007-2008 specifications retain the 7,500-mile or 3-month check interval under normal use conditions but do not include a fluid change interval, meaning only the check schedule is defined for that group.
  • The RT8709 listed in the 2007-2008 row carries a 12.3-liter capacity. A separate RT8709B variant appears only in the 2003-2006 row at 11.8 liters, indicating a capacity difference between the two suffix variants of the same base transmission series.

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