Product Description
Interstate-McBee M-3975818 Oil Cooler – 07.5–24 6.7L & 03–07 5.9L Cummins (Aftermarket Replacement)
Direct-fit oil cooler for Cummins ISB 5.9L (2003–2007) and ISB 6.7L (mid-2007½–2024). Restores proper engine oil temperature control to protect bearings, pistons, and turbocharger. Quality aftermarket replacement by Interstate-McBee.
- OE-style performance: Meets factory flow and heat-rejection requirements.
- Reliability: Brazed plate assembly for consistent cooling and long service life.
- Direct bolt-on: Uses the factory housing; no modifications required.
- Cost-effective: Interstate-McBee quality at a better value than OEM-boxed parts.
Specifications
| Brand | Interstate-McBee |
| Part Number | M-3975818 |
| OEM Reference | Cummins 3975818 |
| Application | Engine oil cooler core |
| Sold As | Each (oil cooler core only unless noted) |
What’s Included
- (1) Oil cooler core, P/N M-3975818
Gaskets/seals are typically not included—add them separately to complete the job.
Vehicle Fitment
Always verify by engine serial number (ESN) when possible.
- Cummins ISB 6.7L (24-valve): mid-2007½–2024
- Ram 2500/3500/4500/5500 pickup & cab-and-chassis
- Cummins ISB 5.9L (24-valve): 2003–2007
- Ram 2500/3500
Recommended/Related Parts
- Oil cooler gasket/seal kit
- Engine oil filter & fresh oil
- Coolant (flush/replace if contaminated)
- Oil cooler housing O-rings/fasteners as needed
Install Notes
- Drain coolant and engine oil; keep passages and mating surfaces clean.
- Inspect and replace all O-rings/gaskets; torque fasteners to Cummins spec.
- After installation, fill fluids, prime oil system, and check for leaks.
- Change oil & filter again shortly after repair if there was cooler failure/contamination.
Why Buy From CPP Diesel
- ESN-verified fitment help from diesel specialists
- Fast shipping, easy returns, competitive pricing
- Deep inventory of complimentary ISB service parts
FAQ
Does this include the housing?
No. This listing is for the cooler core only. Reuse your housing and add a gasket/seal kit.
How do I confirm fitment?
Match to Cummins ref. 3975818 and verify by ESN. Contact us if you need assistance.
Should I flush the system?
Yes. If a cooler failed or oil/coolant mixed, flush both systems and replace filters to prevent repeat issues.
