If you’re dealing with a Chrysler, Dodge, or Jeep vehicle from the 1980s through the early 2000s, chances are you’ve come across the STP S16 oil filter.
It’s a common replacement for engines that originally called for a Fram PH16, featuring the same 3/4″-16 thread and a gasket size that fits older V6 and V8 Mopar engines.
Whether you’re maintaining a classic Jeep Cherokee XJ, a Dodge Ram 1500, or a Chrysler minivan, this filter is one of the go-to options. But which vehicles specifically use it, and what should you keep in mind when replacing it? Let’s break it down.
Primary Dodge/Chrysler (Mopar) Applications
The STP S16 oil filter is a common replacement for older Dodge, Chrysler, and Jeep engines, particularly those built before the early 2000s.
It shares the same 3/4″-16 thread size and gasket dimensions as the Fram PH16, making it a direct fit for several classic Mopar powertrains.
Many Dodge Ram trucks and vans from the 1980s to 2002 use this filter, particularly those equipped with 5.2L (318 cid) and 5.9L (360 cid) Magnum V8s. However, in 2003, Dodge switched to metric-threaded filters (M22x1.5) for most models.
The same applies to certain 3.9L V6 models. These engines were widely used across Dodge’s lineup, from full-size pickups to work vans, making the S16 a reliable maintenance choice.
The STP S16 fits Jeep 4.0L inline-six engines up to 1990. However, starting in 1991, Jeep switched to a metric-threaded oil filter (M20x1.5), so later models will require a different filter.
Some AMC V8s (such as the Jeep 304 and 360) from the 1980s and earlier may accept the STP S16, but many originally used a larger filter (Fram PH11 / WIX 51515). While the S16 fits, many owners prefer the larger filter for better oil capacity and filtration. Always verify fitment before installation.
Certain 1990s Dodge Caravan and Plymouth Voyager models with the 3.3L and 3.8L V6 engines used the STP S16.
However, by the early 2000s, Chrysler minivans began transitioning to metric-threaded filters (M20x1.5), with most making the switch by 2001–2002, so always verify thread size before installation.
However, some models switched to a shorter canister, so checking the existing filter size is always recommended before installation.
Technical Specs and Considerations
The STP S16 oil filter follows the standard Mopar design, offering reliable compatibility with older Dodge, Jeep, and Chrysler engines.
• Thread Size: 3/4″-16, matching the standard Mopar oil filter thread pattern.
• Gasket Diameter: Approximately 2.8 inches, ensuring a secure seal on most Mopar applications.
• Filter Height: Around 4.3 inches, making it a mid-sized spin-on filter commonly used in trucks and SUVs.
• Bypass Valve & Anti-Drainback Valve: Includes an internal bypass valve to maintain oil flow under high pressure. Features an anti-drainback valve, which helps retain oil in the filter when the engine is off, preventing dry starts.
The STP S16 has a bypass valve pressure of 8–11 PSI, similar to the Fram PH16 and WIX 51085. However, some OEM Mopar filters (such as MO-090) have a bypass pressure of 11–13 PSI.
While this is usually insignificant for daily driving, vehicles that tow heavy loads or operate at high RPMs may benefit from using a filter with OEM-matching bypass pressure.
While this difference is minor for most daily drivers, vehicles that operate at higher RPMs or under heavy loads (e.g., towing, off-roading) may benefit from an OEM-matching bypass pressure.
For stock applications, it’s a suitable replacement, but for performance engines or extreme conditions, some owners may prefer filters with enhanced filtration media.
Benefits of Using the STP S16 Oil Filter
The STP S16 is a practical choice for many older Chrysler, Dodge, and Jeep models, offering reliability and broad compatibility.
One of its biggest advantages is availability. Since it cross-references with well-known filters like the Fram PH16 and WIX 51085, it’s easy to find at most auto parts stores.
This makes it a convenient option for those maintaining classic trucks, SUVs, or vans that still use the traditional 3/4″-16 thread.
Another key benefit is its OEM-style fitment. Designed to meet or exceed factory specifications, it offers a direct replacement for many Mopar filters, ensuring proper oil flow and pressure.
The anti-drainback valve helps prevent dry starts, which is crucial for maintaining long-term engine health, especially in vehicles that sit for extended periods between uses.
For everyday driving, towing, or light off-road use, the STP S16 provides reliable filtration and durability at a reasonable cost. It’s a straightforward solution for maintaining older engines without needing to modify the oil system.
Potential Limitations of the STP S16 Oil Filter
While the STP S16 is a solid choice for many older Dodge, Chrysler, and Jeep models, there are a few factors to consider before using it.
One of the main concerns is filter height and clearance. Some vehicles have tight engine bays, and the S16 is a mid-sized filter. If space is limited, a shorter alternative like the STP S3614 (or WIX 51348) may work.
If additional oil capacity is preferred, a taller option such as STP S8A (WIX 51515 or Fram PH8A) may be suitable.
Another consideration is bypass valve pressure differences. While the S16 includes a built-in bypass and anti-drainback valve, its exact pressure settings might differ slightly from some OEM or high-performance filters.
This is usually not an issue for daily driving, but for extreme conditions—like heavy towing or high-revving applications—some owners may prefer a filter with a bypass valve that exactly matches factory specifications.
Lastly, not all Mopar engines use this style of filter. While many older 3.9L, 5.2L, and 5.9L engines accept the 3/4″-16 thread, some models from the late 2000s and newer transitioned to metric-threaded filters. Always double-check your vehicle’s specific requirements before installing an oil filter.
Final Thoughts
The STP S16 oil filter is a reliable option for older Dodge, Chrysler, and Jeep engines that require a 3/4″-16 thread filter. It serves as a direct replacement for the Fram PH16 and similar filters, making it easy to find and install.
However, fitment varies by engine and model year, so always confirm your vehicle’s specifications before purchasing.
If clearance is an issue, a shorter filter might be necessary. Likewise, drivers with high-performance or extreme-use vehicles may prefer a filter with an OEM-matching bypass valve.
For everyday use, the STP S16 is a solid choice if your engine still uses the 3/4″-16 thread. However, many late 1990s and 2000s Dodge/Jeep/Chrysler engines switched to metric-threaded filters (M20x1.5), so always verify thread size before installing. Just make sure you’re getting the right filter for your setup to keep your engine running smoothly.