Disclosure: As an Amazon Associate, we earn from qualifying purchases. If you click a link on this page and make a purchase, we may receive a small commission at no extra cost to you.
Choosing an oil filter by brand name alone can lead to the wrong thread, gasket, or bypass-valve setting for your engine. The K&N Select Oil Filter SO-2004 is a vehicle-specific spin-on filter that combines a high-capacity pleated medium with an advertised service life of up to 20,000 miles. This review explains its verified dimensions, valve design, oil compatibility, installation needs, and fitment limits. Its strongest point is long-service potential, while its biggest risk is buying it without checking your exact year and engine.
Quick Verdict
Rating: 8.1/10
Best For: Drivers with a confirmed SO-2004 application who want a high-capacity spin-on filter for synthetic, conventional, blended, or high-mileage oil.
Bottom Line: The SO-2004 offers useful long-life features, including an anti-drainback valve, a bypass valve, high-capacity pleated media, and an up to 20,000-mile protection claim. It is not universal, and it lacks the welded removal nut found on K&N’s performance-focused HP-series filters.
| Specification | Detail |
|---|---|
| Brand | K&N |
| Model | SO-2004 |
| Product type | Vehicle-specific spin-on engine oil filter |
| Filter media | K&N High Flow Premium Media; the Amazon listing describes pleated synthetic-blend media |
| Filtration claim | Captures 99% of contaminants greater than 30 microns, according to the product listing |
| Service-life claim | Up to 20,000 miles, while following the vehicle and oil manufacturer’s change interval |
| Oil compatibility | Synthetic, conventional, blended, and high-mileage motor oils |
| Height | 3.2 inches (81 mm) |
| Outside diameter | 3.766 inches (96 mm) |
| Thread specification | 3/4 inch-16 UNS |
| Gasket material | Nitrile rubber |
| Valves | Anti-drainback valve and bypass valve |
| Relief-valve range | 11 to 17 PSI |
| Removal nut | No; the fluted canister is designed for a traditional filter wrench |
| Weight | 0.8 lb (0.3 kg) |
| Warranty | K&N 1-year limited warranty |
| Vehicle compatibility | Vehicle-specific fit; the Amazon title highlights select Dodge, Chrysler, Jeep, and Mitsubishi models |
| Safety note | Confirm the year, make, model, engine, and current application guide before installation. |
Key Takeaways
- The SO-2004 is a spin-on filter with a 3/4 inch-16 UNS thread, a nitrile gasket, and a 3.2-inch canister height.
- It has both an anti-drainback valve and an 11 to 17 PSI bypass relief valve.
- K&N rates it for synthetic, conventional, blended, and high-mileage oils.
- The product listing claims up to 20,000 miles of engine protection and 99% efficiency for contaminants greater than 30 microns.
- Fitment is the deciding factor. A matching thread alone does not prove that the gasket size, valve setting, and application are correct.
What Is the K&N Select Oil Filter SO-2004?
The K&N Select Oil Filter SO-2004 is a disposable spin-on oil filter made for specific vehicle applications. K&N positions the Select line for professional installers and service providers, but it also works for home maintenance when the part number matches your engine.
Its fluted canister accepts a common filter wrench, while the internal pleated medium is designed to balance oil flow, contaminant capacity, and service life. Unlike the K&N HP-2004, this model does not include a welded removal nut. That simpler design may suit routine maintenance, but it gives you one less removal option if the filter is installed too tightly.
Before You Buy: Do not rely only on the vehicle brand, filter diameter, or 3/4 inch thread. Confirm the SO-2004 against your exact year, model, engine, and application guide because the bypass setting and gasket dimensions also affect safe fitment.
Who Should Buy It?
Best For
- Drivers whose exact vehicle and engine are listed for SO-2004 fitment.
- Owners using synthetic, conventional, blended, or high-mileage motor oil.
- Buyers who want higher-capacity filtration without paying for a welded removal nut.
Skip If
- You cannot confirm the exact application for your engine, including any diesel or special-duty version.
- You specifically want K&N’s welded hex removal nut for easier access.
- Your warranty or maintenance plan requires an OEM filter or a different approved part number.
Fit and Compatibility
The SO-2004 uses a 3/4 inch-16 UNS thread, measures 3.2 inches tall, and has a 3.766-inch outside diameter. Those measurements help you identify the filter, but they are not a complete fitment test. Two filters can share similar dimensions while using different gasket sizes, flow characteristics, or relief-valve settings.
The Amazon title highlights select Dodge, Chrysler, Jeep, and Mitsubishi models. Its longer application list covers specific years and engines, not every vehicle sold under those brands. The same filter may also appear in cross-reference data for older vehicles from other makes, which makes a current vehicle lookup more reliable than a general brand list.
Fit Check Before Ordering
- Enter the full year, make, model, and engine in the seller’s fitment tool.
- Compare SO-2004 with the part number in your owner’s manual, service information, or current K&N catalog.
- Check whether your engine uses a spin-on filter or a cartridge element.
- Do not assume a gasoline application also covers a diesel engine in the same vehicle line.
Filtration Performance and Oil Flow
The listing claims that the SO-2004 captures 99% of contaminants greater than 30 microns. That efficiency statement is useful for comparing the product’s advertised filtration level, but it does not mean every particle in the oil is removed. Very small particles can remain in circulation, and filter performance also depends on flow, loading, oil condition, and service time.
K&N calls the medium High Flow Premium Media, while the Amazon listing describes it as pleated synthetic-blend filtration media. The pleats increase usable surface area, which helps the filter hold contaminants without creating excessive restriction too early in its service life.
Anti-Drainback and Bypass Valves
The anti-drainback valve helps limit oil from draining out of the filter when the engine is off, when the installation position and engine design use that function. The bypass valve is rated at 11 to 17 PSI. It can provide an alternate oil path if the medium becomes too restrictive, such as during cold starts or heavy loading.
These valves are another reason not to choose a filter only by thread size. Your engine’s oil system is designed around a specific filter application and pressure range.
Materials and Build Quality
The SO-2004 uses a spin-on canister with a fluted outer shape, a nitrile-rubber gasket, and internal high-flow media. K&N lists the filter at 0.8 lb. The design includes both anti-drainback and bypass valves, but no extra O-ring and no welded removal nut.
The fluted shape is practical for a cup-style or band-style oil-filter wrench. Build quality appears aimed at normal and extended maintenance intervals rather than racing-service convenience. Buyers who want a heavy-duty canister and welded nut should compare the compatible HP-series model instead.
Installation and Maintenance
Install the SO-2004 only after confirming fitment and reviewing your vehicle’s oil-change procedure. Drain the oil safely, remove the old filter, and make sure the old gasket did not remain stuck to the mounting surface. A double gasket can cause a major leak soon after startup.
Clean the mounting pad, apply a light film of clean motor oil to the new gasket when directed, and thread the filter on by hand. Follow the tightening instructions printed on the filter or listed in the service manual. Do not use a wrench to force the filter tighter than specified.
Checks After Installation
- Refill with the correct oil grade and quantity.
- Start the engine and confirm the oil-pressure warning light goes out normally.
- Inspect the gasket area for active seepage or drips.
- Shut the engine off, wait as directed, and recheck the oil level.
- Inspect again after a short drive, especially when using a new filter part number.
Pro Tip: Keep the empty filter box until you finish the leak check. It gives you the exact part number, thread specification, and purchase details if you need to confirm an installation issue.
How It Performs in Real Use
For Daily Driving
For commuting and routine errands, the SO-2004 offers a straightforward combination of anti-drainback protection, bypass capability, and compatibility with common oil types. Its value depends more on correct fit and a sensible service interval than on performance branding.
For Extended Oil-Change Intervals
The up to 20,000-mile claim is the main reason to choose this filter over a basic short-service option. Treat that number as a maximum product claim, not an automatic oil-change schedule. Follow the shortest applicable interval from your vehicle manual, oil manufacturer, filter instructions, and severe-service requirements.
For Cold Starts and Seasonal Driving
The anti-drainback and bypass valves are relevant when oil is thicker during startup or when the filter is mounted where oil could drain back. They do not replace the need for the correct oil viscosity. Using an oil grade that is too thick for the weather can affect flow even with the right filter.
For Older or Higher-Mileage Engines
The filter works with high-mileage oil, but it cannot repair sludge, worn bearings, weak oil pressure, or leaking seals. If an older engine has warning lights, unusual valvetrain noise, or heavy contamination, shorten the service interval and have the lubrication system inspected rather than relying on a long-life filter claim.
Compatibility and Safety Notes
Oil-filter errors can cause rapid oil loss or poor lubrication. Stop the engine immediately if the oil-pressure warning stays on, the filter area leaks, or the engine develops new mechanical noise after service. Do not keep driving to see whether the problem clears.
K&N lists a 1-year limited warranty for the SO-2004. Warranty coverage does not make an incorrect application safe, so keep your receipt and fitment record. When retailer warranty metadata conflicts with the manufacturer’s current specification, check K&N’s terms before relying on a stated period.
Pros and Cons
Pros
- Advertised for up to 20,000 miles when used within manufacturer service guidance.
- Claims 99% efficiency for contaminants greater than 30 microns.
- Works with synthetic, conventional, blended, and high-mileage oils.
- Includes anti-drainback and bypass valves with an 11 to 17 PSI relief range.
- Fluted spin-on canister works with common filter-wrench styles.
Cons
- Vehicle-specific fit requires a full year-and-engine check.
- No welded removal nut, unlike the compatible K&N HP-series design.
- The 20,000-mile claim may exceed your vehicle’s required oil-change interval.
Customer Feedback
When reading customer reviews, focus on comments from owners with the same year and engine as yours. Fitment feedback is most useful when it identifies the exact vehicle, confirms that the gasket sealed correctly, and reports whether removal was easy at the next service.
Treat claims such as smoother running or better fuel economy cautiously because an oil change replaces both the filter and the oil. A review can confirm installation experience, but it cannot isolate the filter as the cause of every change in engine feel.
Is It Worth the Price?
The SO-2004 sits above a basic economy filter in features and claimed service life. You get verified valve specifications, a high-capacity medium, broad oil-type compatibility, and a 1-year limited manufacturer warranty. That combination makes it a strong value when the application is correct and you plan to use a suitable oil for a longer service interval.
It is less compelling when your vehicle requires frequent severe-service oil changes, because you may replace the filter long before reaching its advertised maximum. It is also not the best K&N option when a welded removal nut is important for your filter location.
How It Compares to Alternatives
The K&N HP-2004 is the closest same-brand alternative for compatible applications. It adds K&N’s welded removal nut and a heavier performance-style design, but it usually costs more. The SO-2004 makes more sense when you want long-life filtration and can use a standard filter wrench.
The WIX 51085XP is another extended-service option worth checking for compatible engines, while an OEM filter may be better when you want the simplest match to dealer maintenance requirements. Every alternative still needs a current year-and-engine fitment check.
Frequently Asked Questions
Is the K&N Select Oil Filter SO-2004 reusable?
No. It is a disposable spin-on oil filter. Replace it at the interval required by your vehicle, oil, driving conditions, or the filter’s maximum service guidance, whichever comes first.
Does SO-2004 fit every Dodge, Chrysler, Jeep, or Mitsubishi?
No. It fits only listed years and engines. Enter the full vehicle information in a current application guide because different engines in the same model can use different filters.
Can I use it with full-synthetic or high-mileage oil?
Yes. K&N lists compatibility with synthetic, conventional, blended, and high-mileage motor oils. The oil still needs to meet your engine’s required viscosity and performance specification.
Can I leave this filter installed for 20,000 miles?
Only when that interval also follows the vehicle and oil manufacturer’s guidance for your driving conditions. Many vehicles require earlier service, especially with towing, repeated short trips, dust, extreme temperatures, or other severe use.
Does the SO-2004 have a removal nut?
No. It has a fluted canister for a traditional oil-filter wrench. Compare the K&N HP-2004 if your application fits and you specifically want the welded hex nut.
Can I use this filter on a diesel engine?
Do not assume diesel compatibility from the vehicle model alone. Use SO-2004 only when the exact diesel engine and year appear in a current K&N or trusted parts application guide.
What is the most common installation mistake?
Leaving the old gasket on the mounting surface can create a double-gasket leak. Also avoid overtightening, cross-threading, or starting the engine before refilling with the correct amount of oil.
What warranty does K&N list for SO-2004?
K&N’s official SO-2004 specification lists a 1-year limited warranty. Review the current warranty terms and keep your purchase record because retailer metadata can display different information.
The Bottom Line
The K&N Select Oil Filter SO-2004 is recommended with caveats for drivers who confirm exact fitment and want a high-capacity spin-on filter that works with several oil types. Its main strengths are its verified valve design, long-life claim, and practical fluted canister. Skip it when the application is uncertain, an OEM-only filter is required, or you want the HP-series removal nut.
Ready to Buy?
Confirm your exact vehicle and engine, then check the latest product details before you decide.
