WIX 51791 vs FRAM PH49A: Oil Filter Compatibility
Compare WIX 51791 and FRAM PH49A 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.
Quick verdict
Large gasket OD variation · Large gasket ID variation
- 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 51791 and FRAM PH49A specifications
| Specification | WIX 51791 | FRAM PH49A |
|---|---|---|
| Thread size | 11/8-16 | 1"1/8-16 |
| Gasket OD | 100.8 mm | 102 mm |
| Gasket ID | 91.11 mm | 92 mm |
| Can OD | 108.8 mm | 107.7 mm |
| Height | 263.27 mm | 263.91 mm |
| Internal bypass valve | Yes | Yes |
| Bypass PSID | 13 - 19 | 12 |
| Anti-drainback valve | Yes | Yes |
What matters most in this comparison?
Thread match: A direct spin-on substitute starts with the same thread size. If the threads differ, the comparison stops there.
Gasket fit: Even when thread size matches, the gasket outside diameter and inside diameter still control whether the filter seals safely against the mounting surface.
Height difference: Small height differences may be acceptable, but longer filters can create clearance problems in tighter installations.
Valve behavior: Bypass and anti-drainback differences can matter in real-world service, especially on cold start or in applications sensitive to oil drain-back.
Related filter pages
- WIX 51791 oil filter cross reference
- FRAM PH49A oil filter cross reference
- WIX 51791MP oil filter cross reference
- WIX 51791XD oil filter cross reference
- WIX 57791 oil filter cross reference
- WIX 51737 oil filter cross reference
- WIX 51800 oil filter cross reference
- Fleetguard LF3675 oil filter cross reference
Before substituting, verify thread fit, gasket sealing dimensions, height clearance, bypass behavior, and anti-drainback requirements for your specific application.