2021 International LT Coolant Capacity & Type
Comprehensive guide for your 2021 International LT coolant system.
AI-generated reference. Always verify torque values, fluid capacities, intervals, and procedures against the manufacturer's service manual or OEM repair information before performing work. Repairius is not liable for damage from acting on this content without verification.
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The 2021 International LT holds approximately 40-60 quarts (37.9-56.8 liters) of coolant, depending on the engine and specific cooling system configuration.
Quick Answer
- Total Cooling System Capacity: 40-60 quarts (37.9-56.8 liters)
- OEM Coolant Spec: Predominantly OAT (Organic Acid Technology) or NOAT (Nitrited Organic Acid Technology) ELC (Extended Life Coolant) in red, pink, or purple. Always verify with your owner's manual or International service information for the exact specification, often meeting Navistar MPAP (Material Performance & Application Practice) specifications such as MPAP B-0051 Type II or ASTM D6210 for heavy-duty applications.
- Mix Ratio: Typically 50/50 pre-mix or 50% concentrate mixed with 50% distilled water.
Capacity by Engine Option
The 2021 International LT can be equipped with various engine options, primarily International A26 or Cummins X15 engines, each having slightly different cooling system capacities. The following provides general ranges; consult your vehicle's specific owner's manual for precise figures.
| Engine Type | Approximate Capacity (Quarts) | Approximate Capacity (Liters) |
|---|---|---|
| International A26 | 40-50 | 37.9-47.3 |
| Cummins X15 | 50-60 | 47.3-56.8 |
These figures can also vary based on radiator size, presence of auxiliary coolers, and specific chassis configurations.
Flush Interval
For the 2021 International LT, using an Extended Life Coolant (ELC) as specified, the flush interval is significantly longer than older coolant types:
- Normal Duty: Typically 600,000 miles, 12,000 hours, or 6 years, whichever comes first.
- Severe Duty (e.g., heavy hauling, frequent idling, extreme temperatures): It is prudent to monitor coolant condition more frequently and consider a flush and refill closer to 300,000-400,000 miles, 6,000-8,000 hours, or 3-4 years.
Always follow the maintenance schedule provided in your owner's manual or International's service guidelines, as these can include coolant filter replacements (if applicable) and SCA (Supplemental Coolant Additive) testing/replenishment for non-ELC systems (less common with 2021 models but good to be aware of if previous coolant types were used).
How to Refill & Bleed
Refilling and bleeding a heavy-duty cooling system like that in the International LT requires careful attention to detail to prevent air pockets, which can cause overheating. Here
More specs for the 2021 International LT
Oil Capacity & Filter
Capacity, weight, filter PN, drain plug torque, change interval.
Fluid Type Specs
Engine oil, coolant, ATF, diff, brake, PS, DEF — with OEM spec numbers.
Transmission Fluid & Service
Trans model, fluid spec, capacity, filter PN, service interval.
Torque Specifications
Lug nuts, drain plug, caliper, axle nut, plug, key fasteners.
Brake Pad & Rotor Specs
Pad PNs, rotor size, min thickness, caliper torque.
Tire Size & Pressure
OEM size, cold psi, bolt pattern, wheel size, TPMS.
Battery Size & Group
Group size, CCA, AGM/flooded, dimensions, reset note.
A/C Refrigerant & Oil
R-134a or R-1234yf, charge oz, PAG oil spec.
Bulb Sizes (Headlight, Tail, Fog)
Headlight, fog, tail, turn, reverse, interior.
Factory Maintenance Schedule
Service intervals by mileage, severe-duty notes, known issues.
Towing Capacity & Payload
Max tow, payload, GVWR/GCWR, hitch class by trim.
Fuse Box Diagram & Amperage
Fuse box locations, layout, amps, and what each fuse controls.
Serpentine Belt Routing & Length
Belt routing, length, rib count, OEM + aftermarket PNs.
Wheel Alignment Specifications
Camber, caster, toe ranges (front & rear), adjustability notes.
Paint Color Codes
All factory colors with paint codes, sticker location, touch-up tips.
Wiper Blade Sizes
Driver/passenger/rear blade size, attachment, OEM + cross-refs.
Spark Plug Type & Gap
Plug PN, gap, torque, interval by engine.
Transmission & Axle Gear Ratios
Trans gear ratios, axle ratios, RPO codes, tow vs MPG impact.
Key Fob Programming
DIY programming steps, FCC ID, fob PN, battery, transponder.
Same spec — other model years
Maintenance & repair guides
2021 International LT Maintenance Schedule →
Available maintenance guidance; confirm the manufacturer schedule.
Repair planning references →
Plan the scope of work; detailed procedures need configuration-matched evidence.
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