15W-40 Heavy Duty Diesel Oil, 1 Gallon (3.78L), API CK-4 Certified. 15W-40 is the long-standing standard for diesel pickup trucks — Ram Cummins, Ford Power Stroke, and GM Duramax all commonly specify this grade for conventional or synthetic-blend service. Apex Auto Spare Parts stocks CK-4 certified 15W-40 ready to ship across Canada and the US.
Quick Specs (Heavy Duty Diesel Engine Oil 15W-40 — 1 Gallon — Cummins, Power Stroke, Duramax)
| Viscosity Grade | 15W-40 |
| Type | Conventional / Synthetic Blend (heavy duty diesel) |
| API Certification | CK-4 — backward compatible with CJ-4, CI-4 |
| Container Size | 1 US Gallon (3.78 Litres) |
| Recommended Interval | 8,000–16,000 km depending on use — severe duty (towing) shortens interval |
Common Applications
- Ram 2500/3500 — 6.7L Cummins, 5.9L Cummins
- Ford F-250/F-350/F-450 — 6.7L, 6.4L, 6.0L Power Stroke
- Chevy/GMC 2500HD/3500HD — 6.6L Duramax
- Most pre-2017 diesel pickups specify 15W-40 as standard
⚠️ CK-4 vs FA-4: Newer diesel engines (2017+) may specify the thinner FA-4 oils for fuel economy. CK-4 is backward compatible with older specs (CJ-4, CI-4) but check your owner’s manual if your truck is 2017 or newer — it may call for FA-4 specifically.
Why CK-4 Matters
- CK-4 oils offer improved oxidation resistance and shear stability over older CJ-4 specs
- Better protection against oil aeration — important for high-pressure common-rail diesel injection systems
- Backward compatible — safe to use in older diesel engines that specified CJ-4 or CI-4
Severe Service Considerations (Heavy Duty Diesel Engine Oil 15W-40 — 1 Gallon — Cummins, Power Stroke, Duramax)
- Frequent towing, hauling, or extended idling shortens recommended oil change intervals — follow severe duty schedule
- Diesel oil darkens faster than gasoline engine oil due to soot loading — this is normal and doesn’t necessarily mean immediate change is needed
- Always check oil level and condition before long trips, especially in winter
Not sure which oil your engine needs?
Call or WhatsApp us with your year, make, model & engine — we confirm the correct viscosity and spec before you order.
📞 💬 WhatsAppQuestion:
- What oil viscosity does my Cummins, Power Stroke, or Duramax need?
- Should I use 15W-40 or 5W-40 in cold weather?
- What’s the difference between API CK-4 and CJ-4 diesel oil?
- Is full synthetic diesel oil worth the extra cost?
- Can I use 15W-40 in a newer diesel truck with a DPF?
- How often should I change the oil in a diesel truck?
- Does Cummins recommend a specific oil brand or just a spec?
- Is store-brand 15W-40 as good as premium brands like Rotella or Amsoil?
- What oil capacity does a 6.7L Cummins or 6.6L Duramax take?
- Can I switch between 15W-40 and 5W-40 with the seasons?
Questions About Heavy Duty Diesel Engine Oil 15W-40 — 1 Gallon — Cummins, Power Stroke, Duramax
Will this part fit my vehicle?
Fitment depends on the exact year, model, configuration and factory options. Send your VIN and the product link to Apex Auto Spare Parts for confirmation before purchase.
What is included with this product?
Use the product photographs and written listing to confirm the included components. Ask for current inventory photographs when any detail is unclear.
Can this part be shipped across Canada or the United States?
Shipping is available to many Canadian and US destinations. Large body parts and truck beds require a separate freight quote based on size, location and unloading requirements.
How should I confirm condition before ordering?
Review all gallery photographs and request close-up images of mounting points, underside areas and visible cosmetic wear. Used parts may show normal signs of prior use.
