Baldwin B39 vs NAPA Gold 1581: Oil Filter Compatibility
Compare Baldwin B39 and NAPA Gold 1581 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.
Baldwin B39 and NAPA Gold 1581 specifications
How matching is scored| Specification | Baldwin B39 | NAPA Gold 1581 |
|---|---|---|
| Thread size | 13/16-16 | 13/16-16 |
| Gasket OD | 71.4 mm | 69 mm |
| Gasket ID | 62.7 mm | 62 mm |
| Can OD | 93.7 mm | 92.96 mm |
| Height | 111.1 mm | 131.5 mm |
| Internal bypass valve | No | Yes |
| Bypass PSID | Not applicable | 8 - 11 |
| Anti-drainback valve | Yes | Yes |
What matters in this specific comparison
Thread size matches: both are 13/16-16.
Gasket OD differs by 2.4 mm (Baldwin B39: 71.4 mm, NAPA Gold 1581: 69 mm).
Gasket ID differs by 0.7 mm (Baldwin B39: 62.7 mm, NAPA Gold 1581: 62 mm).
NAPA Gold 1581 is 20.4 mm taller (Baldwin B39: 111.1 mm, NAPA Gold 1581: 131.5 mm) -- check clearance before substituting.
Can OD differs by 0.7 mm (Baldwin B39: 93.7 mm, NAPA Gold 1581: 92.96 mm).
Bypass valve presence differs: NAPA Gold 1581 has one, Baldwin B39 does not.
Open related filters
Before substituting, verify thread fit, gasket sealing dimensions, height clearance, bypass behavior, and anti-drainback requirements for your specific application.