Caterpillar CT trucks, CT

Automatic transmission fluid capacity & service interval

Caterpillar CT trucks use automatic transmission fluid with a capacity range of 25 to 49 liters. Service intervals include 12000 miles, 6 months, or 500 hours; 25000 miles, 12 months, or 1000 hours; 75000 miles, 36 months, or 3000 hours; and 150000 miles, 36 months, or 3000 hours. The data covers 8 configurations.

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

Type	Specifications
CT660 4x4, CT13 EPA 10 (2014- )	Use: Severe Capacity 25 liter Capacity 45 liter (Initial fill) Capacity 49 liter (Initial fill with retarder) Capacity 27 liter (with retarder) Change 12000 miles/ 6 months/ 500 hours Code: Caterpillar CX31 6/1
CT660 4x4, CT13 EPA 10 (2014- )	Use: Severe, extended Capacity 25 liter Capacity 45 liter (Initial fill) Capacity 49 liter (Initial fill with retarder) Capacity 27 liter (with retarder) Check 12000 miles/ 6 months/ 500 hours Change 75000 miles/ 36 months/ 3000 hours Code: Caterpillar CX31 6/1
CT660 4x4, CT13 EPA 10 (2014- )	Use: On-road use Capacity 25 liter Capacity 45 liter (Initial fill) Capacity 49 liter (Initial fill with retarder) Capacity 27 liter (with retarder) Check 12000 miles/ 6 months/ 500 hours Change 25000 miles/ 12 months/ 1000 hours Code: Caterpillar CX31 6/1
CT660 4x4, CT13 EPA 10 (2014- )	Use: On-road use, extended Capacity 25 liter Capacity 45 liter (Initial fill) Capacity 49 liter (Initial fill with retarder) Capacity 27 liter (with retarder) Check 12000 miles/ 6 months/ 500 hours Change 150000 miles/ 36 months/ 3000 hours Code: Caterpillar CX31 6/1
CT660 6x6, CT13 EPA 10 (2014- )	Use: Severe Capacity 25 liter Capacity 45 liter (Initial fill) Capacity 49 liter (Initial fill with retarder) Capacity 27 liter (with retarder) Change 12000 miles/ 6 months/ 500 hours Code: Caterpillar CX31 6/1
CT660 6x6, CT13 EPA 10 (2014- )	Use: Severe, extended Capacity 25 liter Capacity 45 liter (Initial fill) Capacity 49 liter (Initial fill with retarder) Capacity 27 liter (with retarder) Check 12000 miles/ 6 months/ 500 hours Change 75000 miles/ 36 months/ 3000 hours Code: Caterpillar CX31 6/1
CT660 6x6, CT13 EPA 10 (2014- )	Use: On-road use Capacity 25 liter Capacity 45 liter (Initial fill) Capacity 49 liter (Initial fill with retarder) Capacity 27 liter (with retarder) Check 12000 miles/ 6 months/ 500 hours Change 25000 miles/ 12 months/ 1000 hours Code: Caterpillar CX31 6/1
CT660 6x6, CT13 EPA 10 (2014- )	Use: On-road use, extended Capacity 25 liter Capacity 45 liter (Initial fill) Capacity 49 liter (Initial fill with retarder) Capacity 27 liter (with retarder) Check 12000 miles/ 6 months/ 500 hours Change 150000 miles/ 36 months/ 3000 hours Code: Caterpillar CX31 6/1

Additional Notes

The Caterpillar CT660 with the CT13 EPA 10 engine carries a service fill capacity of 25 liters for the automatic transmission, rising to 27 liters when a retarder is present, reflecting the additional fluid volume the retarder circuit holds during normal operation.
Initial fill capacity on the CT660 automatic transmission reaches 45 liters, and 49 liters when a retarder is installed. Initial fill figures represent the total fluid volume required when filling a dry or overhauled transmission, which is substantially higher than a routine service fill because fluid has not yet distributed through all internal passages and cooler circuits.
The gap between the 25-liter service fill and the 45-liter initial fill on the CT660 automatic transmission is 20 liters, illustrating how much fluid remains retained in the system between drain intervals under normal service conditions.
Under severe use conditions, the CT660 4x4 and 6x6 both specify an automatic transmission fluid change interval of 12,000 miles, 6 months, or 500 hours, whichever comes first, with no fluid check interval listed separately for that condition.
Under severe extended use conditions, the change interval extends to 75,000 miles, 36 months, or 3,000 hours, while a fluid check is still required at 12,000 miles, 6 months, or 500 hours throughout that extended period.
On-road use conditions on both the CT660 4x4 and 6x6 call for a fluid change at 25,000 miles, 12 months, or 1,000 hours, paired with a check interval of 12,000 miles, 6 months, or 500 hours.
The on-road extended interval pushes the change interval to 150,000 miles, 36 months, or 3,000 hours, which is double the standard on-road change mileage and six times the severe use change mileage, while retaining the same 12,000-mile check interval.
The 4x4 and 6x6 drivetrain configurations of the CT660 share identical automatic transmission fluid capacities and service intervals across all four use conditions, indicating no specification difference between the two axle arrangements for this system.