Engine oil is the lifeblood of a heavy truck engine. This guide walks through API class, SAE viscosity and drain intervals for heavy duty diesel engines.
Key takeaway: prefer API CI-4 or higher with SAE 15W-40, then adjust the drain interval by duty cycle and verify with the OEM data.
1. Start with the API class
CI-4, CJ-4 and CK-4 are the mainstream heavy duty diesel classes; later letters mean newer emission compliance and better oxidation stability.
2. Then the SAE viscosity
15W-40 covers most climates; 10W-40 suits severe cold regions while 20W-50 fits hot climates and heavy loads.
3. Set the drain interval by duty cycle
Severe duty (overload, dust, short hauls) shortens the interval; highway line-haul can extend it. Always replace the filter together.
4. Buy from a traceable channel
We supply OEM and branded oils with traceability, supporting bulk purchase and export.