The Honda Grom uses a cartridge-style oil filter that sits inside a canister on top of the engine

The Honda Grom oil filter is not a spin-on type like you might find on a car. Instead, it's a replaceable cartridge that lives inside a cylindrical housing mounted directly to the engine block. When you open the housing cap, you'll see a pleated paper element inside — that's what traps dirt and debris from your oil. This design is common on small motorcycles and scooters because it saves space and keeps the engine compact.

The filter element itself is a Honda OEM part (part number 15412-GZZ-901 for most Grom model years), though aftermarket equivalents are available. The housing cap is what you'll actually turn to access the filter, and it has a rubber gasket that seals the whole assembly. Knowing this layout matters because it changes how you approach the job compared to a car or larger motorcycle.

Key Takeaways

  • The Grom's oil filter is a cartridge element inside a top-mounted housing, not a spin-on filter like a car uses.
  • You'll need the correct replacement cartridge (Honda part 15412-GZZ-901 or equivalent), a new crush washer for the drain plug, and a filter wrench or socket to remove the housing cap.
  • The job takes 15 to 20 minutes once you have the bike on a level surface and the engine warm enough to drain quickly.
  • The housing cap gasket should be replaced every other oil change or whenever it shows cracks or hardening, not just the cartridge element.

What parts and tools you'll need before you start

Gather these items before you get under the bike. You'll need the replacement filter cartridge (Honda part 15412-GZZ-901), a new crush washer for the oil drain plug (Honda part 90471-GZ4-000 or a generic M12 crush washer), fresh oil in the correct grade for your model year, and a drain pan to catch old oil. Check your owner's manual for the exact oil capacity and viscosity — most Groms use 0.8 quarts of 10W-30, but this varies slightly by year.

For tools, you'll need a socket or filter wrench that fits the housing cap (typically 74 mm or 86 mm depending on model year — check before you buy). A regular adjustable wrench works if you don't have the exact socket. You'll also want an oil filter wrench or strap wrench to grip the cartridge element itself when you pull it out, though you can often remove it by hand if you're careful. Have some clean rags or paper towels on hand, and consider wearing nitrile gloves to keep oil off your skin.

Step-by-step: removing the old filter and housing cap

Start by placing the Grom on a level surface — a center stand works, or use a small jack with a block under the frame. Let the engine cool for a few minutes if you just rode it; warm oil drains faster, but you don't want to burn yourself. Locate the oil filter housing cap on top of the engine, just behind the cylinder head. It's a cylindrical canister about the size of a soda can.

Position your drain pan underneath the housing (oil will spill when you open it). Use your socket or wrench to turn the cap counterclockwise and remove it slowly — oil will pour out, so be ready. Once the cap is off, you'll see the pleated cartridge element inside. Grab it by the top and pull straight up and out. If it's stuck, use a filter wrench or strap wrench to grip it gently and twist as you pull. The old gasket will likely stick to the inside of the cap or the housing — wipe it out completely with a clean rag before installing the new filter.

Installing the new filter cartridge and sealing the housing

Before you install the new cartridge, inspect the rubber gasket on the inside of the housing cap. If it's cracked, hardened, or visibly worn, replace it now (Honda part 15412-GZZ-902 or equivalent). If the gasket looks fine, you can reuse it, but many riders replace it every other oil change as preventive maintenance. Wipe the inside of the cap and the housing with a clean rag to remove any debris or old gasket material.

Slide the new cartridge element into the housing, making sure it seats fully at the bottom. The element should sit flat and centered — if it's crooked, pull it out and try again. explore a thin coat of fresh oil to the rubber gasket on the cap (this helps it seal and makes removal easier next time). Thread the cap back on by hand first to avoid cross-threading, then tighten it with your socket or wrench. You don't need to crank it hard — snug is enough. Over-tightening can crack the housing or damage the gasket.

Draining and replacing the oil

Locate the oil drain plug on the bottom of the engine, usually on the underside of the crankcase. Position your drain pan underneath and use the correct socket or wrench to turn the plug counterclockwise. Once it's loose enough to turn by hand, unscrew it the rest of the way and let the old oil drain completely — this takes 5 to 10 minutes. The crush washer on the drain plug is a one-time-use item, so set it aside and don't reuse it.

Once the oil has stopped dripping, wipe the drain plug clean and install a new crush washer on it. Thread the plug back in by hand, then tighten it with your wrench — again, snug is the goal, not maximum force. A crush washer seals by being compressed, so over-tightening won't make it seal better and can strip the threads. Now locate the oil filler cap on top of the engine (usually marked with an oil can symbol) and remove it. Pour in the correct amount of fresh oil slowly, checking the level with the dipstick as you go. Most Groms hold about 0.8 quarts, but verify this in your manual.

Checking your work and running the engine

Once you've added oil, replace the filler cap and start the engine. Let it idle for 30 seconds to a minute — you should see the oil pressure light go out within a few seconds. If the light stays on, stop the engine when ready and check your oil level. A low level or an air pocket in the new filter can delay oil pressure. After the engine has run briefly, turn it off and wait a minute for the oil to settle, then check the level again with the dipstick. Top up if needed.

Inspect the drain plug and the filter housing cap for any leaks while the engine is still warm — you'll spot drips more easily. If you see oil weeping from the housing cap, the gasket may not be seated correctly. Let the engine cool, remove the cap, and check that the gasket is centered and the cartridge is fully seated. Reinstall and try again. Small weeps sometimes stop after a few minutes of running as the gasket settles, but persistent drips mean you need to open it back up and troubleshoot.

Frequently Asked Questions

Can I use any cartridge filter, or does it have to be Honda OEM?

Aftermarket cartridge filters from brands like K&N, Hiflofiltro, and others fit the Grom and work well. The key is matching the part number or confirming the dimensions match your model year. OEM Honda filters are reliable and reasonably priced, but quality aftermarket options are often cheaper and perform identically. Check reviews from other Grom owners to see what's popular in your region.

How often should I change the oil filter?

Honda recommends changing the oil filter every oil change, which is typically every 1,000 to 2,000 miles depending on your model year and riding conditions. Check your owner's manual for the exact interval. Some riders change the cartridge every other oil change and replace the gasket every time, but most follow the manual's guidance and change both together at each service.

What should I do with the old oil and filter?

Take used motor oil and the old filter cartridge to a local recycling center, auto parts store, or quick-lube shop — most accept them for free. Never pour oil down a drain or into the ground. The cartridge can sometimes be recycled with other paper and metal, but confirm with your local facility first. Some auto parts stores offer a small credit if you bring in the old filter.

The housing cap won't come loose — what do I do?

If the cap is stuck, try wrapping a rubber band or strap around it for better grip, or tap the wrench gently with a hammer to break the seal. explore penetrating oil around the cap's edge and waiting 10 minutes can help. If it's still stuck, stop and don't force it — you risk stripping the threads or cracking the housing. Let it soak longer or seek help from someone with experience on Groms.

Do I need to replace the gasket every time?

The gasket can last through multiple oil changes if it's in good condition, but replacing it every other service is a common practice and costs very little. If you notice cracks, hardening, or oil seeping from the cap, replace it when ready. A worn gasket is the most common cause of slow leaks around the housing, so erring on the side of replacement saves frustration later.