Cooling, Lubrication, and Filtration Products
This domain covers the fluids and filters that keep the engine and drivetrain alive. Candidates must understand specification-driven selection: the right part is the one that meets the OEM specification, not just the one that fits.
Cooling
- Coolant chemistry: conventional (green), OAT, and HOAT; mixing chemistries can cause gelling and liner pitting.
- Components: radiator, water pump, thermostat, hoses, and surge tank. Match by engine and application.
Lubrication
- Engine oil: viscosity grade and API/engine OEM specification (e.g., CK-4, E6/E9).
- Gear lube and ATF: axle and transmission fluids are specification-specific; wrong fluid can damage components.
- Grease: NLGI grade and base soap matter for chassis and wheel-end use.
Filtration
- Oil, fuel, air, and cabin filters: match by part number and micron rating; some fuel systems require specific water-separation capability.
- Filter change intervals are OEM-specified; using a non-spec filter can void warranty.
Traps in questions
- Mixing coolant chemistries.
- Substituting a generic oil that meets viscosity but not the OEM spec.
- Using a fuel filter without the required water separator on common-rail systems.
Rule of thumb
Specification first, fit second. A filter or fluid that physically fits but does not meet the OEM specification is the wrong part.