MAHLE OC 978 vs FRAM PH4558: Oil Filter Compatibility
Compare MAHLE OC 978 and FRAM PH4558 oil filters by compatibility, dimensions, thread size, gasket fit, bypass valve, anti-drainback valve status, and match confidence. Use this comparison as a fitment review, not as an automatic substitution guarantee. Both use a M20x1.5 thread.
Quick verdict
Closest known dimensional difference: height +5.5 mm. Verify application-specific requirements before substituting.
- Thread size is the first hard-fit check for any comparison of spin-on filters.
- Gasket OD and gasket ID are the most important seal-related dimensions.
- Height differences can matter for clearance even when thread and gasket fit appear close.
- Bypass and anti-drainback differences may be important, depending on the application.
MAHLE OC 978 and FRAM PH4558 specifications
How matching is scored| Specification | MAHLE OC 978 | FRAM PH4558 |
|---|---|---|
| Thread size | M20x1.5 | M20x1.5 |
| Gasket OD | 70.8 mm | 71 mm |
| Gasket ID | 62.3 mm | 61 mm |
| Can OD | 75 mm | 76 mm |
| Height | 79.5 mm | 85 mm |
| Internal bypass valve | Yes | Yes |
| Bypass PSID | 14 | 12 |
| Anti-drainback valve | Yes | Yes |
What matters in this specific comparison
Thread size matches: both are M20x1.5.
Gasket OD differs by 0.2 mm (MAHLE OC 978: 70.8 mm, FRAM PH4558: 71 mm).
Gasket ID differs by 1.3 mm (MAHLE OC 978: 62.3 mm, FRAM PH4558: 61 mm).
FRAM PH4558 is 5.5 mm taller (MAHLE OC 978: 79.5 mm, FRAM PH4558: 85 mm) -- check clearance before substituting.
Can OD differs by 1 mm (MAHLE OC 978: 75 mm, FRAM PH4558: 76 mm).
Both open their bypass valve in a comparable range: MAHLE OC 978 at 14-14 psi, FRAM PH4558 at 12-12 psi -- these ranges do not overlap.
Open related filters
Before substituting, verify thread fit, gasket sealing dimensions, height clearance, bypass behavior, and anti-drainback requirements for your specific application.