WIX 51318 vs NAPA Gold 1381: Oil Filter Compatibility
Compare WIX 51318 and NAPA Gold 1381 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 M20x1.5 thread.
Quick verdict
Closest known dimensional difference: height -42 mm. Verify application-specific requirements before substituting.
- 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.
WIX 51318 and NAPA Gold 1381 specifications
How matching is scored| Specification | WIX 51318 | NAPA Gold 1381 |
|---|---|---|
| Thread size | M20x1.5 | M20x1.5 |
| Gasket OD | 64.47 mm | 63 mm |
| Gasket ID | 56.49 mm | 55 mm |
| Can OD | 93.29 mm | 92.99 mm |
| Height | 122 mm | 80 mm |
| Internal bypass valve | Yes | Yes |
| Bypass PSID | 8 - 11 | 12 - 15 |
| Anti-drainback valve | Yes | Yes |
What matters in this specific comparison
Thread size matches: both are M20x1.5.
Gasket OD differs by 1.5 mm (WIX 51318: 64.47 mm, NAPA Gold 1381: 63 mm).
Gasket ID differs by 1.5 mm (WIX 51318: 56.49 mm, NAPA Gold 1381: 55 mm).
WIX 51318 is 42 mm taller (WIX 51318: 122 mm, NAPA Gold 1381: 80 mm) -- check clearance before substituting.
Can OD differs by 0.3 mm (WIX 51318: 93.29 mm, NAPA Gold 1381: 92.99 mm).
Both open their bypass valve in a comparable range: WIX 51318 at 8-11 psi, NAPA Gold 1381 at 12-15 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.