2019 International LT Fluid Type Specifications

As an ASE-certified master technician, I've compiled this comprehensive fluid specification sheet for the 2019 International LT. Adhering to manufacturer specifications for all fluids is critical for optimal performance, longevity, and to maintain your warranty. Using incorrect fluids can lead to premature wear, component failure, and costly repairs.

Quick reference

Engine Oil

For the 2019 International LT, the engine oil requirements are critical for the longevity of its heavy-duty diesel engine. The primary specifications will be API CK-4 or, for certain engines, API FA-4. Always consult your owner's manual for the specific API classification recommended for your engine model. The choice between CK-4 and FA-4 often depends on the engine design and desired fuel economy characteristics; FA-4 oils are typically lower viscosity for improved fuel efficiency in newer engines.

Viscosity: Common viscosity grades include SAE 10W-30 and SAE 15W-40. The appropriate viscosity will depend on the ambient operating temperatures and your engine manufacturer's recommendations. Always refer to the owner's manual for the precise recommendations for your specific engine (e.g., Cummins, Navistar, or Detroit Diesel).

Capacity: Engine oil capacities for heavy-duty trucks like the International LT can range significantly, typically between 38 and 48 quarts (9.5 to 12 gallons), depending on the specific engine model and oil pan size. Always verify the exact capacity in your owner's manual and use the dipstick for final confirmation.

Intervals and Pitfalls: Engine oil change intervals for heavy-duty diesel trucks are typically extended compared to passenger vehicles, often ranging from 20,000 to 50,000 miles or more, depending on duty cycle, oil analysis results, and engine manufacturer guidelines. Always follow the manufacturer's recommended service intervals. Crucially, never mix API CK-4 and FA-4 oils. While both are designed for diesel engines, their chemical compositions are different, and mixing them can degrade performance and protection.

Engine Coolant

The 2019 International LT requires a heavy-duty, extended-life organic additive technology (OAT) coolant. Navistar typically specifies its own "Navistar Premium EC-1 Heavy Duty Coolant," which meets or exceeds ASTM D6210 and TMC RP-329 standards. This coolant is generally red or pink in color. The EC-1 specification indicates an extended-life coolant engineered for heavy-duty diesel applications, providing superior protection against cavitation, corrosion, and scaling.

Capacity: Coolant capacities for these large trucks are substantial, usually in the range of 60 to 70 quarts (15-17.5 gallons), varying by radiator size and specific engine configuration. Always top off with the correct coolant type and concentration.

Intervals and Pitfalls: Extended-life OAT coolants can last for 600,000 miles, 6 years, or 12,000 hours, whichever comes first, with proper SCA (Supplemental Coolant Additive) testing and replenishment if recommended, though many modern OAT coolants are "fill for life" with no SCA requirement for the initial fill. The most significant pitfall is mixing different types of coolants, especially OAT with conventional inorganic additive technology (IAT) or hybrid OAT (HOAT) coolants. This can lead to chemical reactions, gel formation, additive drop-out, and severe corrosion, compromising the cooling system