MAHLE OC 25 vs Bosch 3421: Oil Filter Compatibility
Compare MAHLE OC 25 and Bosch 3421 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 3/4-16 thread.
Quick verdict
Both use a 3/4-16 thread.
- 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 25 and Bosch 3421 specifications
How matching is scored| Specification | MAHLE OC 25 | Bosch 3421 |
|---|---|---|
| Thread size | 3/4-16 | 3/4-16 |
| Gasket OD | 71 mm | 70 mm |
| Gasket ID | 61.7 mm | 61 mm |
| Can OD | 93.98 mm | 75.01 mm |
| Height | 98.55 mm | 120.4 mm |
| Internal bypass valve | Yes | Yes |
| Bypass PSID | 32 | 25 - 35 |
| Anti-drainback valve | Yes | Yes |
What matters in this specific comparison
Thread size matches: both are 3/4-16.
Gasket OD differs by 1 mm (MAHLE OC 25: 71 mm, Bosch 3421: 70 mm).
Gasket ID differs by 0.7 mm (MAHLE OC 25: 61.7 mm, Bosch 3421: 61 mm).
Bosch 3421 is 21.9 mm taller (MAHLE OC 25: 98.55 mm, Bosch 3421: 120.4 mm) -- check clearance before substituting.
Can OD differs by 19 mm (MAHLE OC 25: 93.98 mm, Bosch 3421: 75.01 mm).
Both open their bypass valve in a comparable range: MAHLE OC 25 at 32-32 psi, Bosch 3421 at 25-35 psi.
Open related filters
Before substituting, verify thread fit, gasket sealing dimensions, height clearance, bypass behavior, and anti-drainback requirements for your specific application.