The two oil filters in your image are AC Delco models: the PF64 (GM part #25206966) on the left and the PF48 (GM part #12737086) on the right. While they appear visually identical in terms of external size, shape, threads (both use 22mm threads), and canister design—which is why they're often confused—they are not interchangeable due to internal differences in specifications.
### Key Differences:
- **Bypass Valve Pressure**: This is the main functional distinction. The PF64 has a higher bypass valve opening pressure of 22 PSI (150 kPa), while the PF48 is rated at 15 PSI (100 kPa). The bypass valve allows unfiltered oil to flow if the filter becomes clogged, and the higher pressure on the PF64 is designed for engines with specific performance demands to ensure better filtration under higher stress.
- **Applications**:
- The PF64 is typically the OEM (original equipment manufacturer) filter for newer GM vehicles, such as certain Chevrolet Corvettes (e.g., with LT1 engines), Malibus (2.5L), and some Camaros or trucks from 2014 onward. It's engineered for engines requiring higher bypass thresholds.
- The PF48 is used in older GM models, like pre-2014 Silverados, Malibus, or other V6/V8 engines where the lower bypass pressure suffices.
- **Internal Design**: Beyond the bypass, the PF48 may have a slightly different bypass mechanism overall, though both are spin-on filters with similar filtration media. The PF64 is sometimes noted as having a bit more capacity in some contexts, but this varies by source.
- **Service Replacements**: Note that the PF64 is often replaced in service with the PF63E (a longer version with matching specs), while the PF48 has been superseded by the PF48E in some cases, but with the same core function.
GM explicitly advises against swapping them, as using the wrong one could lead to improper oil flow or reduced engine protection, especially in high-performance setups.
