Baldwin B281 vs FRAM HP1: Oil Filter Compatibility
Compare Baldwin B281 and FRAM HP1 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.
Baldwin B281 and FRAM HP1 specifications
How matching is scored| Specification | Baldwin B281 | FRAM HP1 |
|---|---|---|
| Thread size | 3/4-16 | 3/4"-16 |
| Gasket OD | 71.4 mm | 71 mm |
| Gasket ID | 62.7 mm | 61 mm |
| Can OD | 93.7 mm | 95 mm |
| Height | 136.5 mm | 143 mm |
| Internal bypass valve | Yes | Yes |
| Bypass PSID | 20 | 22 |
| Anti-drainback valve | Yes | Yes |
What matters in this specific comparison
Thread size matches: both are 3/4-16.
Gasket OD differs by 0.4 mm (Baldwin B281: 71.4 mm, FRAM HP1: 71 mm).
Gasket ID differs by 1.7 mm (Baldwin B281: 62.7 mm, FRAM HP1: 61 mm).
FRAM HP1 is 6.5 mm taller (Baldwin B281: 136.5 mm, FRAM HP1: 143 mm) -- check clearance before substituting.
Can OD differs by 1.3 mm (Baldwin B281: 93.7 mm, FRAM HP1: 95 mm).
Both open their bypass valve in a comparable range: Baldwin B281 at 20-20 psi, FRAM HP1 at 22-22 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.