Bosch 3421 vs NAPA Gold 1582: Oil Filter Compatibility
Compare Bosch 3421 and NAPA Gold 1582 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.
Bosch 3421 and NAPA Gold 1582 specifications
How matching is scored| Specification | Bosch 3421 | NAPA Gold 1582 |
|---|---|---|
| Thread size | 3/4-16 | 3/4-16 |
| Gasket OD | 70 mm | 69 mm |
| Gasket ID | 61 mm | 62 mm |
| Can OD | 75.01 mm | 74.19 mm |
| Height | 120.4 mm | 115 mm |
| Internal bypass valve | Yes | Yes |
| Bypass PSID | 25 - 35 | 8 - 11 |
| 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 (Bosch 3421: 70 mm, NAPA Gold 1582: 69 mm).
Gasket ID differs by 1 mm (Bosch 3421: 61 mm, NAPA Gold 1582: 62 mm).
Bosch 3421 is 5.4 mm taller (Bosch 3421: 120.4 mm, NAPA Gold 1582: 115 mm) -- check clearance before substituting.
Can OD differs by 0.8 mm (Bosch 3421: 75.01 mm, NAPA Gold 1582: 74.19 mm).
Both open their bypass valve in a comparable range: Bosch 3421 at 25-35 psi, NAPA Gold 1582 at 8-11 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.