STP oil filters work in most vehicles that take the same thread size and bypass valve rating, but you need to match three things: the filter diameter, the connection type, and the pressure relief setting

STP makes filters under the Fram brand (Fram owns STP), and they use standard SAE thread sizes that fit thousands of vehicles. The challenge is not that STP filters are unusual — it is that you need to know what your vehicle actually needs before you can find what matches it. A cross reference tells you which other brand filters will work in place of an STP filter, or which STP filter replaces a filter you already know fits your car.

The most direct route is to look up your vehicle's year, make, and model in the STP or Fram filter finder on their website, or to take your current filter to an auto parts store and ask them to match it by size and thread. If you have an STP filter number already, you can search that number in cross reference databases to see what Fram, Motorcraft, Mobil 1, Bosch, or other brands offer the same fit.

Key Takeaways

  • STP filters use standard SAE threads, so many other brands fit the same engine — you match by filter diameter, thread size, and bypass valve pressure, not by brand alone.
  • The fastest way to find a match is to enter your vehicle's year, make, and model into the STP or Fram filter finder, which returns the correct part number.
  • If you have an STP part number, you can search it in cross reference tools like Fram's website, RockAuto, or your local auto parts store's computer to see equivalent filters from other makers.
  • Bypass valve pressure matters — a filter rated for 8 PSI will not protect your engine the same way as one rated for 10 or 12 PSI, so check the spec sheet before switching brands.
  • Counterfeit STP filters exist, so buy from established retailers like auto parts chains, Walmart, or Amazon rather than unknown sellers.

How STP Filter Numbers and Sizes Work

STP filter part numbers usually start with a letter code that hints at the filter type. For example, S3614 or S4636 are common STP numbers. The number itself does not tell you the vehicle — you have to look it up. The physical filter has a diameter (usually between 2.5 and 3.5 inches), a height (usually 4 to 5 inches), and a thread size stamped or printed on the top or bottom.

The thread size is the most important number for cross referencing. Most car engines use either 3/4-16 UNF (the most common) or M20x1.5 (metric, common on imports). Trucks and some larger engines use 13/16-16 UNF. If you match the thread size and diameter, the filter will physically fit. The bypass valve pressure — printed on the filter as "8 PSI", "10 PSI", or "12 PSI" — determines when the filter lets unfiltered oil through if the filter gets clogged. This number should match your engine's design.

Using the STP and Fram Websites to Find Your Filter

The STP website has a filter finder tool at stp.com. You enter your vehicle's year, make, model, and engine size, and it returns the correct STP part number and a brief description of the filter type (standard, high-mileage, synthetic, etc.). Write down the part number — you will need it if you want to cross reference to other brands.

Fram owns STP, so the Fram website (fram.com) has the same database and will show you both Fram and STP options for your vehicle. Fram also publishes a cross reference guide that lists which Fram filters match which STP numbers. If you already own an STP filter and want to know what Fram equivalent exists, you can search the STP number in Fram's cross reference tool and it will show you the Fram part number that fits the same engine.

Cross Referencing STP to Other Major Brands

Once you have your STP part number or the physical dimensions of your current filter, you can find matches from Mobil 1, Bosch, Purolator, Motorcraft, or Valvoline. RockAuto.com has a cross reference tool where you can enter an STP number and see what other brands offer the same fit. AutoZone and O'Reilly Auto also have cross reference databases in their stores and online.

The most reliable method is to call or visit a local auto parts store with your STP part number or your vehicle information. Their computer system is built to cross reference, and they can tell you in seconds what Mobil 1, Bosch, or Motorcraft filters fit your engine. They can also confirm the bypass valve pressure, which is harder to find in online databases.

Be aware that not every brand makes a filter for every engine. Some vehicles have very few options, while popular trucks and sedans may have a dozen. If an STP filter is the only one in stock, that is often because it is the cheapest option or the store stocks it by default — not because it is the only one that fits.

What to Check Before Buying a Cross Reference Filter

When you find a filter from another brand that cross references to your STP, verify three things before you buy. First, check the thread size on the new filter's box or spec sheet — it must match your engine's filter head. Second, check the bypass valve pressure. If your engine calls for 10 PSI and the cross reference filter is rated 8 PSI, it will open earlier when the filter clogs, letting unfiltered oil through. Third, check the filter height and diameter — they should be within a quarter inch of your original filter.

The spec sheet is usually printed on the box or available on the manufacturer's website. If you cannot find it, ask the store. A filter that is slightly taller or shorter may still fit, but one that is the wrong thread size will not screw on at all, and one with the wrong bypass pressure may not protect your engine properly during cold starts or high-mileage operation.

Why You Might Need a Cross Reference Instead of STP

The most common reason to cross reference away from STP is price. STP filters are mid-range in cost, but Fram (the same company) often costs less, and store-brand filters from Walmart or Costco are sometimes cheaper still. If you want a synthetic or high-mileage filter, you may find better options from Mobil 1 or Bosch, which specialize in those categories.

Availability is another reason. If your local store is out of the STP filter your vehicle needs, a cross reference tells you what they do have in stock that will work. During supply shortages, knowing how to cross reference can save you a trip to another store or a long wait for a reorder.

Some drivers prefer certain brands for warranty or performance reasons. Mobil 1 filters come with a longer warranty than STP in some cases, and Bosch filters are known for high bypass valve pressure, which some people prefer for older engines. Cross referencing lets you choose the brand that matches your priorities without guessing whether it will fit.

Avoiding Counterfeit STP Filters

Counterfeit STP filters exist, especially on third-party marketplaces. A fake filter may have a slightly different label, misspelled text, or a thread that does not match the spec sheet. The safest way to avoid counterfeits is to buy from established retailers: auto parts chains like AutoZone, O'Reilly, Advance Auto Parts, or NAPA; big-box stores like Walmart or Costco; or Amazon with the "Ships from and sold by Amazon" label.

If you buy from a smaller seller or marketplace, check the reviews and seller rating. Counterfeit filters are rare enough that they usually show up in reviews as "thread did not fit" or "filter leaked." If the price is significantly lower than the major retailers, that is a warning sign — STP filters are commodity products, and the price does not vary much between legitimate sellers.

Frequently Asked Questions

Can I use a Fram filter instead of STP if they are the same part number?

Yes. Fram owns STP, and many STP filters are made by Fram or are identical to Fram filters. If the part numbers cross reference, the filters are the same or equivalent. Check the box to confirm they have the same thread size and bypass pressure.

What does the bypass valve pressure number mean?

The bypass valve opens when the filter gets too clogged to let oil through at normal pressure. A 10 PSI bypass means the valve opens at 10 pounds per square inch, letting unfiltered oil flow to protect the engine. Higher pressure (12 PSI) means the filter can get dirtier before the bypass opens. Your engine's design calls for a specific pressure — do not guess.

If I have an STP filter on my car now, can I just look at it to find a cross reference?

Yes. The part number is printed on the filter, usually on the top or side. Write it down and search it in a cross reference tool, or take the filter to an auto parts store and they will match it. You can also measure the diameter and thread size and match those, but the part number is faster.

Are cheaper cross reference filters as good as STP?

If they have the same thread size and bypass pressure, they will protect your engine the same way. Cheaper filters may use lower-grade media or have a shorter lifespan, but the core function — filtering oil and protecting the engine — is the same. Read reviews for the specific filter you are considering.

Where can I find a cross reference if the STP website does not have my vehicle?

Call an auto parts store with your vehicle's year, make, model, and engine size. Their computer system can cross reference any filter. You can also search your vehicle in the Fram, Mobil 1, or Bosch filter finders — if they have a filter for your engine, you can cross reference it back to STP using their tools.