What Size Socket Is Needed for the Oil Filter on the BMW F30 340i?

The oil filter housing cap on a BMW F30 340i typically requires a 27 mm socket (or a 27 mm oil filter cap socket) to remove and reinstall it correctly. This size applies to the N55 and B58 engines used in the 340i lineup, but owners should still visually confirm fitment before applying force.

Understanding the BMW F30 340i Oil Filter Setup

The BMW F30 340i, depending on market and model year, is equipped with either the N55 (early production/335i-style setups) or the B58 engine. Both engines use a top-mounted, cartridge-style oil filter housed in a plastic or composite cap located on the top/front of the engine. The cap has a large hex molded into it, which is where the socket is used for removal and installation.

Engine Types and Applicability

Most owners asking about the F30 340i oil filter socket size are dealing with the B58 engine used widely in the later F30 340i models. However, BMW’s modern straight-six turbo engines share a very similar filter housing design, and the 27 mm size has become an informal standard for these caps. Regardless of engine code, the housing cap for the F30 340i oil filter is designed around a 27 mm hex.

The Correct Socket Size: 27 mm

The correct size for the oil filter housing cap on the BMW F30 340i is 27 mm. Using this socket allows you to safely loosen and tighten the cap without rounding it or damaging the plastic.

Why 27 mm Matters

The 27 mm size is large enough to fully engage the molded hex on the oil filter cap, distributing torque evenly. Using the wrong size — even something that feels “close” like 1-1/16 inch — can result in slipping, rounding, or cracking the cap. Replacement caps are not outrageously expensive, but a damaged cap during an oil change can turn a straightforward job into a delay or a tow.

Recommended Tools for the Job

To carry out an oil change on a BMW F30 340i safely and efficiently, several basic tools are especially useful beyond just the correct socket size.

• 27 mm socket or oil filter cap socket: Preferably a 6-point socket to ensure a solid grip on the plastic cap.
• 3/8″ or 1/2″ drive ratchet: Depending on the socket you buy; some filter sockets are specifically 3/8″ drive.
• Torque wrench: To tighten the oil filter housing cap to factory spec (commonly around 25 Nm / ~18 ft-lb for similar BMW housings; check your specific manual).
• Drain pan: Large enough to catch all engine oil, typically more than 6 liters capacity.
• New filter kit: Usually includes the cartridge filter, large O-ring for the cap, and often a small crush washer for the drain plug.
• Gloves and rags: To keep hands clean and wipe down any spilled oil.

Together, these tools help ensure that the oil change is performed cleanly, that the cap is installed to the proper torque, and that damage to the plastic components is avoided.

Tips for Safely Removing and Reinstalling the Oil Filter Cap

Using the correct socket is just one part of a safe and clean oil filter service; technique also plays a crucial role in preventing damage and leaks.

1. Ensure full engagement of the socket: Seat the 27 mm socket fully on the hex before applying torque to prevent slipping.
2. Use steady, controlled force: Avoid sudden jerks when breaking the cap loose, as the cap is plastic and can crack if stressed.
3. Loosen the cap before draining all the oil: Cracking the cap slightly open can help oil drain back into the pan, reducing mess when you pull the filter.
4. Replace the O-ring: Always swap the old O-ring for the new one included with the filter, and lubricate it lightly with fresh oil before reinstalling.
5. Do not overtighten: Use a torque wrench and follow the service manual spec. Overtightening can deform or crack the cap and cause leaks.
6. Inspect for leaks after startup: After the oil change, run the engine, then check around the filter housing for any signs of oil seepage.

Following these steps with the proper 27 mm socket greatly reduces the risk of damaging the housing or creating future oil leaks, and it helps keep the job professional and repeatable.

Why Socket Fit and Quality Matter

While the number — 27 mm — is clear, the quality and design of the socket used can have practical consequences, especially given the plastic filter cap in the F30 340i.

Standard Socket vs. Dedicated Oil Filter Socket

Owners often debate whether a standard deep 27 mm socket is enough or if a dedicated oil filter cap socket is worth the purchase. A standard deep 27 mm, 6-point socket is typically sufficient and widely available. However, dedicated oil filter cap sockets are shaped to mate more completely with the cap, often surrounding it further down the sides, which can reduce the risk of slipping under high torque or on slightly worn caps. For repeated DIY oil changes, the dedicated filter socket can be a modest but worthwhile investment.

Summary

The oil filter housing cap on the BMW F30 340i uses a 27 mm hex, and a 27 mm socket — ideally a 6-point deep socket or a dedicated oil filter cap socket — is the correct tool for removing and reinstalling it. Combined with careful technique, proper torque, and a fresh O-ring, this ensures a clean, leak-free oil change and prevents damage to the plastic cap on both N55- and B58-equipped F30 340i models.

What size is the oil filter socket on a 2018 BMW 330i?

2017-2024 BMW 330i. Notes: Engine Oil Filter Wrench – 32 mm, 6-Point – 3/8″ Drive.

What size oil filter socket do I need?

The correct oil filter socket size depends on your vehicle, so you must first determine the specific filter’s size. You can find the correct size by checking your vehicle’s owner’s manual, looking up the part number online, or physically measuring the filter with a caliper or ruler. Some common sizes, such as 32mm, may fit certain vehicles like some VW TDIs, but it’s essential to confirm the exact size for your car to ensure a proper fit.
 
This video explains different types of oil filter wrenches, including those that use sockets: 1mYour Home GarageYouTube · Oct 11, 2021
How to determine the correct socket size

• Check your owner’s manual: This is the most reliable method to find the exact oil filter size and the specific wrench needed for your vehicle. 
• Measure the filter: If you don’t have the manual, use a caliper or ruler to measure the outside diameter of the oil filter. You can then use this measurement to find a compatible wrench. 
• Look up the filter part number: Search online for the correct oil filter part number for your car’s make, model, and year. This will often lead to information on the required socket size. 
• Use a universal wrench: If you work on multiple cars, a universal or adjustable oil filter wrench may be a good investment, as it can adapt to various sizes. 

What size socket is the oil filter on a BMW B58?

The B58 engine requires a 32mm socket for the oil filter housing cap. A 17mm socket is also needed for the oil drain plug.
 
You can watch this video for a demonstration of the B58 engine oil and filter change: 59sTop ShevyYouTube · Oct 21, 2024
Required tools

• 32mm socket: This is the key size for removing the B58’s oil filter housing cap. 
• 17mm socket: Needed to remove the oil drain plug. 
• Extensions: Extensions are highly recommended for both the 32mm and 17mm sockets to reach the filter housing and drain plug, which are in tight locations. 
• Torque wrench: A torque wrench is recommended to tighten the drain plug and filter housing to the correct specifications. 

What size socket is the BMW oil filter?

The BMW oil filter socket size depends on the engine, with common sizes being 32mm or 27mm for the filter housing cap, and an 86mm 16-flute wrench for some models. Always confirm the correct size for your specific vehicle before starting maintenance, as some newer models might use the 27mm or a specific 32mm size. 
Common sizes

• 32mm: Frequently used on many BMW engines, including the M52, M54, M57, B58, and others, for removing the oil filter housing cap. 
• 27mm: Some newer four-cylinder engines, such as the B46, B47, and B48, use a 27mm socket for the oil filter cap. 
• 86mm 16-flute wrench: This specialized wrench fits BMW models with an 86mm oil filter housing cap, and it can be used with a 3/8″ drive ratchet or a 27mm socket for some applications. 

How to find the correct size

• Check your owner’s manual: This is the most reliable way to determine the correct socket size for your specific vehicle. 
• Inspect the oil filter housing: Look for the size printed on the top of the filter housing cap. 
• Use a socket wrench: Try a 32mm or 27mm socket to see which one fits your filter housing cap. If neither works, you may need the 86mm 16-flute wrench.