API CK-4 vs CI-4 Diesel Engine Oil: DPF, Older Engines and Compatibility
Understand when CK-4 may replace an older API diesel category, why FA-4 is different, and what DPF-equipped engines require.
Caterpillar 15W-40 Engine Oil Specifications: CI-4, Applications and Pack Sizes
A practical guide to Cat DEO 15W-40 CI-4, Caterpillar part 3E-9848, applicable engine generations and the checks required before use.
