How to Know What Size Oil Filter to Get

You determine the correct oil filter size by matching your vehicle’s make, model, year, and engine to manufacturer specifications, then confirming with a parts catalog, online lookup, or your owner’s manual. In practice, that means you should never guess by appearance alone—different filters can look similar but have crucial differences in thread size, gasket diameter, and internal design that affect engine protection and fitment.

Contents

Why Oil Filter Size Matters More Than It Seems
The Core Factors That Determine Oil Filter Size
The Most Reliable Ways to Find the Correct Oil Filter Size
Common Mistakes When Choosing an Oil Filter
Special Situations: When Choosing a Filter Gets Tricky
How to Double-Check Fit Before Installation
Summary: The Safe Way to Choose the Right Oil Filter Size

Why Oil Filter Size Matters More Than It Seems

Choosing the right oil filter is not just about physical size; it’s about compatibility, oil flow, and filtration efficiency. Using the wrong filter can lead to leaks, poor oil pressure, or even engine damage. That’s why carmakers and filter manufacturers publish very specific part numbers and compatibility charts that drivers should follow closely.

The Core Factors That Determine Oil Filter Size

Before diving into how to find the right filter, it helps to understand what “size” means in this context. It’s not just length and diameter, but a package of specifications that must match your engine’s design.

Key Dimensions and Specifications

These are the main technical characteristics that define an oil filter and must match what your engine is designed for.

Thread size and pitch: The diameter and spacing of the threads that screw onto the engine’s oil filter mount. This must be exact or the filter will not seat or seal properly.

Gasket (seal) diameter: The outer and inner diameter of the rubber sealing ring that presses against the engine block or filter adapter. A mismatch can cause leaks or a failure to seal.

Filter canister length: The physical height of the filter. Too long and it may hit crossmembers or suspension parts; too short and it may reduce oil capacity or impact flow characteristics.

Canister diameter: The width of the filter body, which must clear nearby components like exhaust parts or frame rails.

Bypass valve setting: The pressure at which oil is allowed to bypass the filter element to prevent oil starvation if the filter is restricted, especially at cold starts.

Anti-drainback valve: A built-in rubber or silicone valve on many spin-on filters that prevents oil from draining back out of the filter when the engine is off, improving start-up lubrication.

Filter media capacity and efficiency: How much debris the filter can hold and how small the particles it can trap, usually specified by the manufacturer rather than the automaker.

Taken together, these specifications explain why two filters that look nearly identical can behave very differently on the same engine—underscoring the importance of choosing an exact or approved equivalent part number.

The Most Reliable Ways to Find the Correct Oil Filter Size

There are several safe, widely used methods for identifying the right filter. Most drivers will rely on at least two of them: the owner’s manual and a trusted parts catalog or website.

1. Check Your Owner’s Manual

Your vehicle’s owner’s manual is the manufacturer’s official guide and often includes specific oil filter part numbers or specifications. It may not list every brand, but it provides a baseline you can cross-reference.

When using the owner’s manual, focus on more than just the name of the filter.

Locate the maintenance section: Look for chapters on “Lubrication,” “Engine Oil,” or “Maintenance Schedule.” These pages often list required oil type and recommended filters.

Find the OEM (original equipment) part number: Many manuals list the factory filter part number from the vehicle manufacturer (e.g., Toyota, Ford, GM, Honda).

Note any special requirements: Some engines call for cartridge-style filters, specific pressure-relief values, or special designs for turbocharged engines.

Check regional variations: Manuals sometimes distinguish between markets or engine options, so verify the engine code or displacement matches your car.

Once you have the OEM part number or specification, you can use it as a reference to find compatible filters from other brands without guessing on size or fitment.

2. Use Online Parts Lookups from Major Brands and Retailers

Online databases maintained by filter manufacturers and auto parts retailers are among the most practical modern tools for finding the right filter. They translate your vehicle details into precise part numbers in seconds.

These steps can help you use online lookups accurately and safely.

Start with a reputable website: Use sites from major filter brands (e.g., Fram, Wix, Bosch, Mann, AC Delco, Motorcraft) or national auto parts retailers.

Enter full vehicle details: Include year, make, model, engine size, and sometimes trim level or VIN to ensure an exact match.

Confirm engine variant: Many models have multiple engines in the same year; picking the wrong one can yield the wrong filter size.

Compare multiple brands: After finding one part number, cross-check against a second brand’s lookup to confirm consistency.

Look for notes or warnings: Some catalogs flag “build date splits,” mid-year changes, or special filters for vehicles with tow packages or turbo engines.

Cross-referencing a couple of online catalogs greatly reduces the risk of error and can reveal if a previous owner may have installed a non-standard setup requiring extra caution.

3. Visit a Parts Store and Ask for a Catalog Lookup

In-store parts professionals use similar databases but may also have printed catalogs and experience with odd fitment issues. This can be especially useful for older, modified, or imported vehicles.

To get the most accurate result in person, it helps to come prepared.

Bring your vehicle information: Have the year, make, model, engine size, and VIN (if possible) readily available.

Show your old filter: If you have the previously used filter, the clerk can cross-reference its brand and part number directly.

Ask about alternatives: Many systems list standard, premium, and extended-life options that all share the correct fitment.

Confirm before leaving: Ask the clerk to double-check that the filter fits your exact engine option and build date if noted.

Using a professional lookup adds a layer of human verification, which can be valuable if your vehicle falls in a gray area, such as a mid-year engineering change or aftermarket engine swap.

4. Cross-Reference an Existing Filter Part Number

If you already have a filter you know is correct—often the one you removed from the car—you can use its part number to find equivalent filters from other brands, or to confirm you’re buying the same size again.

Cross-referencing is particularly helpful when switching brands or moving from a basic to a premium filter line.

Locate the part number on the canister: Most spin-on filters have the brand name and part number printed or stamped clearly on the body.

Use manufacturer cross-reference tools: Many filter makers offer “cross-reference” search fields where you input a competitor’s number.

Confirm specs before swapping: If you’re considering a different filter model (e.g., extended-life), compare basic specs such as thread size and gasket diameter.

Watch for “close but not exact” matches: Some cross-references list functional equivalents that may differ in length; confirm they’re approved for your application.

Cross-referencing helps maintain compatibility even if your preferred brand is out of stock, while still preserving proper fit and function.

5. Use the VIN or Engine Code for Precision

For vehicles with multiple engine options, mid-year changes, or global variants, the Vehicle Identification Number (VIN) or specific engine code provides the most accurate way to target the correct filter.

Using more precise identification can prevent common mix-ups that occur when relying on model name alone.

Find the VIN: Usually located on the dashboard near the windshield, driver’s door jamb, or on registration documents.

Provide the VIN to parts stores: Many systems decode VINs to identify exact engine, model year, and manufacturing batch.

Check engine code when relevant: Some brands stamp engine codes on the block; this matters especially for imported, performance, or swapped engines.

Use OEM sites: Some manufacturer websites let you input a VIN to see original parts, including filter part numbers.

Relying on the VIN or engine code can resolve confusion in complex lineups where two different engines share the same model badge but require different oil filter sizes.

Common Mistakes When Choosing an Oil Filter

Missteps in choosing oil filters usually come down to assumptions—judging by looks, using outdated data, or trusting that “close enough” is fine. These errors can lead to messy leaks or more serious engine issues.

Judging by Appearance Alone

Two filters can look almost identical on the shelf yet differ subtly in threads, gasket placement, or internal components. Swapping them based on seemly similar size is risky.

Several visual similarities can be misleading and should not replace proper specification checks.

Same length and width: Filters can share external dimensions but use different thread diameters or pitches.

Similar gasket ring size: A gasket that’s only a few millimeters off can still bolt on but fail to seal properly.

Matching brand family: Within one brand, part numbers that look sequential aren’t necessarily compatible or interchangeable.

Color and branding: Paint color says nothing about fit or function; always verify the part number.

The safest approach is to verify part numbers and specifications instead of trusting that “it looks right” when you hold it next to your old filter.

Assuming Bigger or Smaller Is Always Better

Some enthusiasts experiment with longer or larger-diameter filters for potentially greater capacity, but this is not automatically an upgrade and can introduce problems if the filter isn’t engineered for that engine.

Several non-obvious issues can arise when you deviate from the recommended filter dimensions.

Clearance issues: A longer filter can contact suspension parts, skid plates, or exhaust components, especially under load or engine movement.

Oil pressure changes: Different internal designs and media densities can alter oil flow characteristics.

Bypass valve mismatch: Incorrect bypass pressure can cause unfiltered oil to circulate too often or, conversely, starve the engine in cold conditions.

Warranty concerns: Using unapproved filter sizes may complicate warranty claims if oil-related failures occur.

While some experienced owners and tuners do run alternate filters intentionally, most drivers are better served by sticking with manufacturer-approved part numbers or direct cross-references.

Using Outdated or Generic Fitment Information

Older printed charts, generic “fits most” claims, or non-specific online advice can lag behind updates from automakers and filter manufacturers. Engines, specifications, and recommended parts can change over time.

Reliance on outdated sources can introduce mismatches without the user realizing it.

Superseded part numbers: Manufacturers periodically replace older filters with updated designs that may have improved performance or durability.

Model-year revisions: A filter that fits a 2015 model may not be correct for a visually similar 2018 version.

Aftermarket modifications: Oil cooler kits, relocation adapters, or turbo kits can change the required filter style and size.

Universal claims: Phrases like “fits many imports” or “universal” are red flags without specific application data.

Reconfirming fitment with current, brand-specific catalogs or databases is a simple way to avoid these pitfalls and ensure you are using the latest approved filter.

Special Situations: When Choosing a Filter Gets Tricky

Most everyday vehicles have straightforward filter requirements, but a few scenarios demand extra attention: older classics, performance builds, off-road rigs, or cars with aftermarket oil systems.

Older and Classic Vehicles

For older cars and trucks, parts may no longer be stocked under the original numbers, and catalogs may rely on cross-referenced substitutes. Corrosion on the engine block or non-standard previous work can complicate the process further.

When dealing with age and history, added verification steps can help confirm the correct filter.

Consult enthusiast forums and clubs: Owners’ groups often share tested filter options, especially when original parts are discontinued.

Use specialty catalogs: Some brands maintain dedicated classic or vintage vehicle listings with detailed notes.

Verify mount threads and gasket seat: In rare cases, previous owners may have swapped engines or adapters, changing filter requirements.

Keep a known-good reference: Once you’ve confirmed a correct filter, save the part number and maybe buy a spare.

Patience and extra research up front can save time, money, and headaches when maintaining older engines with more complex histories.

Performance, Towing, and Heavy-Duty Use

Engines used for towing, track days, or heavy-duty work may benefit from filters designed for higher temperatures, higher flow, or extended service intervals—but size and fit must still match OEM specs or approved alternatives.

To handle elevated demands without sacrificing safety, several aspects deserve closer attention.

Check manufacturer-approved upgrades: Some automakers and filter brands offer “severe service” or high-capacity filters for the same fitment.

Confirm bypass and flow ratings: High-performance filters often publish detailed specs; ensure they align with engine requirements.

Integrate with oil type and interval: Extended-life filters are intended to pair with specific synthetic oils and longer drain intervals.

Monitor oil pressure: If you modify the oil system substantially, use gauges to confirm oil pressure remains in safe ranges.

In demanding applications, choosing a performance-oriented filter that still matches the exact size and fitment specifications offers a better balance than experimenting with non-approved dimensions.

Vehicles with Cartridge-Style Filters

Many modern engines use cartridge filters, where only the filter element is replaced while the housing remains. Here, “size” is less about external dimensions and more about internal design and sealing surfaces.

Cartridge systems introduce a few unique concerns compared with traditional spin-on filters.

Match the exact cartridge shape: Cartridges can differ in height, diameter, and end-cap design even if they appear similar.

Replace O-rings and seals: Cartridge kits often include new O-rings that must be installed correctly to prevent leaks.

Observe torque specs: The housing cap should be tightened to the manufacturer’s specified torque to avoid damage or leaks.

Beware of lookalike parts: Filters for different engines in the same family may appear interchangeable but are not.

Following manufacturer instructions closely with cartridge systems is essential; slight deviations in fit or installation can lead to oil seepage or pressure loss.

How to Double-Check Fit Before Installation

Even after identifying the correct part number, a quick verification before installation can prevent surprises. It only takes a few extra minutes to confirm the new filter matches expectations.

Compare the New Filter to the Old One

Visual comparison is not enough on its own, but it’s a useful final safety check once you’re confident in the part number.

These specific checks can help catch packaging or stocking errors before the engine is started.

Match the thread opening: Lay the old and new filters side by side and check that the threaded hole size and internal pattern appear identical.

Inspect gasket location: Ensure the rubber sealing ring is in the same position and appears to be the same diameter.

Check approximate length and diameter: Small differences are sometimes normal, but large changes warrant rechecking the part number.

Verify labeling: Confirm the brand and part number on the filter match the packaging and your reference information.

If anything looks significantly different, it’s worth pausing and reconfirming fitment rather than risking installation of an incorrect filter.

After Installation: Look and Listen for Warning Signs

Once the filter is installed and you’ve added oil, how the engine behaves in the first minutes can confirm that the filter size and fitment are correct.

Monitoring a few simple indicators at startup can alert you quickly to a potential problem.

Check for leaks: With the engine running, inspect the area around the filter for oil seepage or drips.

Watch the oil pressure gauge or light: Ensure pressure rises quickly and no warning lights remain on.

Listen for unusual engine noise: Extended rattling or ticking could indicate delayed oil pressure.

Reinspect after a short drive: After a brief trip, check again for leaks or loose fittings around the filter.

These steps do not change whether the filter is the right model, but they help confirm that the filter is functioning correctly and that installation was done safely.

Summary: The Safe Way to Choose the Right Oil Filter Size

Knowing what size oil filter to get is ultimately about aligning your choice with the vehicle manufacturer’s specifications and verified parts data, not about guessing based on looks or general advice. The critical dimensions—thread size, gasket diameter, canister dimensions, and internal valves—are all baked into the correct part numbers listed in manuals and parts databases.

The safest approach is straightforward: start with your owner’s manual or a trusted online or in-store parts lookup, confirm the part number using your exact vehicle details or VIN, and cross-reference if you change brands. Avoid substituting filters that are merely “close,” and be especially cautious with older, modified, or high-performance vehicles where additional research is warranted. By following these steps, you ensure the filter fits, seals, and performs as intended—protecting your engine and avoiding preventable problems down the road.

How do I know what size oil filter I need?

You can find the correct oil filter size by checking your car’s owner’s manual, which provides the manufacturer’s specifications. Alternatively, you can use online lookup tools by entering your car’s make, model, and year, or by taking your old filter to an auto parts store to match it with a new one.
This video explains how to choose the right oil filter for your car: 59sFlatironsTuningYouTube · May 15, 2023
Methods to find the correct oil filter size

Consult the owner’s manual: This is the most reliable method, as it provides the exact specifications recommended by the vehicle’s manufacturer.
Use online lookups: Many auto parts store websites have a “vehicle finder” tool. You can enter your car’s details (make, model, year, and sometimes engine size) to see a list of compatible filters.
Look up your VIN: You can take your Vehicle Identification Number (VIN) to a dealership, and they can look up the correct part number for you.
Match your old filter: Take the old filter to an auto parts store. The staff can help you find a new one that is compatible with your old one.
Cross-reference part numbers: If you have the part number from your old filter, you can use it to find cross-reference numbers online. For example, searching for “Supertech ST 9688” will show you compatible replacements from other brands.

How do I know if my oil filter will fit?

To know if an oil filter will fit, use your vehicle’s year, make, and model with an online search or a store’s lookup tool, check the owner’s manual, or match the OEM part number. You can also verify dimensions like thread size, seal diameter, and height, but it’s crucial to ensure the thread pitch is correct to prevent engine damage.
This video demonstrates how to properly install an oil filter: 1mDMoney GarageYouTube · Feb 14, 2020
Use a vehicle lookup tool

Online resources: Many auto parts websites and manufacturer sites have a “vehicle lookup” feature where you can enter your car’s year, make, model, and engine to find compatible filters.
In-store: Provide the same vehicle information to a parts store employee, who can quickly find the correct filter for you.

Check your owner’s manual

Consult your car’s owner’s manual for the exact specifications of the recommended oil filter type and size.
You can also often find the original equipment manufacturer (OEM) part number in the manual or on a label under the hood.

Use the OEM part number

Find the OEM part number from your owner’s manual or the old filter.
Use an online “cross-reference” tool to see which aftermarket filters have the same specifications or are a compatible replacement.

This video explains how to verify if an oil filter will fit your car: 45sLive FreeYouTube · Feb 1, 2022
Verify key dimensions

If you have the old filter, check its dimensions, such as the thread size (e.g., M20×1.5cap M 20 cross 1.5𝑀20×1.5), seal diameter, and overall height.
It is critical to ensure the thread size and pitch (SAE or metric) match your engine’s mounting post, as using the wrong threads can cause leaks or damage the engine.

How do I know what size filter I need?

To find the correct dimensions, refer to the measurements printed alongside your existing one. Your current air filter should have the dimensions printed on the side stated in length x width x depth. If you don’t have the dimensions, all you need is a tape measure and to follow these simple steps to accurately measure.

Which oil is thicker, 5W-30 or 5w20?

Yes, 5W-30 is thicker than 5W-20 when the engine is at normal operating temperature. The “30” in 5W-30 indicates a higher viscosity at high temperatures, providing a thicker oil film for better protection, especially under heavy loads or in hot climates. The “20” in 5W-20 signifies a thinner consistency at high temperatures, which can improve fuel efficiency.
Key differences

Feature	5W-30	5W-20
High-temperature viscosity	Thicker, provides more engine protection during high heat and heavy loads	Thinner, leads to better fuel economy and is often recommended for newer, fuel-efficient engines
Cold-start viscosity	Same as 5W-20 (5W), flows quickly for a cold start	Same as 5W-30 (5W), flows quickly for a cold start
Protection	Better protection in high-heat situations and for older or heavy-duty engines	Good for engines designed for it, but may not provide as much protection in high-heat situations as 5W-30
Fuel economy	May slightly decrease fuel economy due to higher viscosity	Generally improves fuel economy due to lower viscosity and less engine resistance