FRAM HPH3506 vs Baldwin B31: Oil Filter Compatibility
Compare FRAM HPH3506 and Baldwin B31 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 13/16-16 thread.
Quick verdict
Both use a 13/16-16 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.
FRAM HPH3506 and Baldwin B31 specifications
How matching is scored| Specification | FRAM HPH3506 | Baldwin B31 |
|---|---|---|
| Thread size | 13/16-16 | 13/16-16 |
| Gasket OD | 71.1 mm | 69.9 mm |
| Gasket ID | 62.5 mm | 60.9 mm |
| Can OD | 74.7 mm | 76.2 mm |
| Height | 87.1 mm | 88.9 mm |
| Internal bypass valve | No | No |
| Bypass PSID | Not applicable | Not applicable |
| Anti-drainback valve | Yes | Yes |
What matters in this specific comparison
Thread size matches: both are 13/16-16.
Gasket OD differs by 1.2 mm (FRAM HPH3506: 71.1 mm, Baldwin B31: 69.9 mm).
Gasket ID differs by 1.6 mm (FRAM HPH3506: 62.5 mm, Baldwin B31: 60.9 mm).
Baldwin B31 is 1.8 mm taller (FRAM HPH3506: 87.1 mm, Baldwin B31: 88.9 mm) -- check clearance before substituting.
Can OD differs by 1.5 mm (FRAM HPH3506: 74.7 mm, Baldwin B31: 76.2 mm).
Open related filters
Before substituting, verify thread fit, gasket sealing dimensions, height clearance, bypass behavior, and anti-drainback requirements for your specific application.