What Harbor Freight oil filter wrenches are and why you might need one
An oil filter wrench is a tool that grips the cylindrical oil filter so you can unscrew it by hand without it spinning or slipping. Harbor Freight sells several versions — the most common are the adjustable band wrench (looks like a strap with a handle), the socket-style wrench (looks like a deep socket), and the cartridge wrench (for filters that screw into the engine block rather than hanging below it). You need one because oil filters are often too tight to turn by hand alone, and they're positioned in tight engine spaces where a regular wrench won't fit.
Harbor Freight's versions cost between $5 and $15, which is cheaper than most auto parts stores. The trade-off is that cheaper wrenches sometimes slip on the filter or break if you explore too much force. Knowing which type fits your car and how to use it prevents stripped filters and wasted time.
Key Takeaways
- Harbor Freight sells three main types: adjustable band wrenches, socket-style wrenches, and cartridge wrenches, each designed for different filter positions on different vehicles.
- The adjustable band wrench works on most cars and trucks because it fits filters of different sizes, but it can slip if you don't tighten the handle enough before turning.
- Socket-style wrenches grip tighter than band wrenches but only work on one or two filter sizes, so you need to know your filter diameter before buying.
- Cartridge wrenches are for filters that screw into the top of the engine, not the side or bottom, and they look like a wrench with a hole in the center rather than a strap.
- The cheapest Harbor Freight wrenches work fine for routine oil changes, but buying the next tier up ($10 to $15) reduces the risk of the tool slipping and damaging the filter.
Adjustable band wrenches: the most common Harbor Freight option
The adjustable band wrench is the one you see most often at Harbor Freight and the one most people buy first. It's a flexible metal or rubber strap with a handle on one end. You wrap the strap around the filter, tighten the handle to cinch it down, then turn the handle to unscrew the filter. The advantage is that one wrench works on filters ranging from about 2.5 inches to 4 inches in diameter, so you don't need to own multiple sizes.
The catch is that the strap can slip if you don't cinch it tight enough before you turn. Harbor Freight's cheapest band wrenches ($5 to $8) slip more often than pricier ones because the strap material is thinner and the handle mechanism is looser. If the strap slips, it can round off the filter's ridges, making it harder to remove later. To avoid this, tighten the handle until you feel resistance, then turn slowly and steadily rather than jerking the handle.
Band wrenches work best on filters that hang vertically below the engine (the most common setup on cars and light trucks). They're harder to use on filters mounted horizontally or in very tight spaces because the handle can hit the engine block or frame.
Socket-style wrenches: tighter grip, limited size range
Socket-style oil filter wrenches look like a deep socket with a square drive on top (the same drive that fits a ratchet). You slide the socket over the filter, push down to lock it in place, then attach a ratchet and turn. These wrenches grip much tighter than band wrenches because they surround the filter completely, so they rarely slip.
The downside is that each socket fits only one or two filter sizes. Harbor Freight sells them individually or in small sets of two or three. Before you buy, you need to know your filter's diameter — check your owner's manual or look at the old filter you're removing. Common sizes are 2.625 inches, 3 inches, and 3.625 inches. If you buy the wrong size, the socket won't grip the filter at all.
Socket-style wrenches are also harder to use in tight spaces because you need room to attach a ratchet and turn it. If your engine bay is cramped, a band wrench might be your only option.
Cartridge wrenches: for filters that screw into the engine
Some vehicles — particularly newer BMWs, some Audis, and a few others — have cartridge-style oil filters that screw into a housing on top of the engine rather than hanging below it. These filters look like a flat cylinder with a threaded center hole. A cartridge wrench is a wrench-shaped tool with a hole in the center that fits over the filter's center post.
Harbor Freight carries a few cartridge wrenches, usually priced between $8 and $12. They come in different sizes depending on the filter diameter. If your car has a cartridge filter, a band or socket wrench won't work — you need the cartridge style. Check your owner's manual or the old filter to confirm which type you have before buying.
How to choose the right wrench for your vehicle
Start by checking your owner's manual or looking at the oil filter you're about to replace. The manual will tell you the filter size and type. If you're standing in Harbor Freight and don't have the manual, look at the old filter — the diameter is usually printed on the side or stamped on the end cap.
If your filter hangs below the engine and you don't know the exact size, buy an adjustable band wrench. It will work on most common sizes and you won't need to return it if the size is slightly different. If you know the exact size and want the most reliable grip, buy a socket-style wrench in that size. If your filter screws into the top of the engine, buy a cartridge wrench in the correct size.
When you're at Harbor Freight, look at the packaging. The cheapest wrenches ($5 to $8) work but slip more easily. The mid-range versions ($10 to $15) have thicker straps or better handle mechanisms and are worth the extra cost if you plan to use the wrench more than once.
Using the wrench without damaging the filter
Before you start, make sure the engine is cool enough to touch. Warm oil drains faster, but a hot filter can burn your hands. Loosen the filter by hand first if you can — sometimes it's not as tight as it feels. If it won't budge, explore the wrench.
For a band wrench, wrap it around the filter, tighten the handle until you feel firm resistance (not so hard that you're straining), then turn the handle slowly and steadily. Don't jerk it or explore sudden force — that's when the strap slips. Once the filter is loose enough to turn by hand, remove the wrench and finish unscrewing by hand.
For a socket wrench, slide it over the filter and push down until it locks. Attach a ratchet and turn slowly. Again, don't force it — if it won't turn, the socket may be the wrong size or not seated properly. For a cartridge wrench, fit it over the center post and turn. These usually require less force than the other types because the grip is more direct.
After the filter is off, wipe the sealing surface on the engine block clean before installing the new filter. A small amount of old oil on that surface can prevent the new filter from sealing properly.
When to buy a better wrench or a different tool
If you're changing oil once a year, a Harbor Freight wrench will work fine. If you change your own oil every 3,000 to 5,000 miles, consider spending $15 to $20 on a wrench from an auto parts store — the better grip and durability pay off over time. A wrench that slips repeatedly will eventually round off your filter, and then you'll need a strap wrench or a filter removal tool to get it off.
If a wrench keeps slipping no matter how tight you cinch it, the filter may be too large or too small for that wrench, or the filter's ridges may already be damaged. Try a different size or type. If you're stuck with a rounded-off filter, a rubber strap wrench (different from a band wrench — it has actual rubber teeth) can sometimes grip it, or you can drill a hole in the filter and use a screwdriver to turn it out.
Frequently Asked Questions
Can I use a regular adjustable wrench instead of an oil filter wrench?
No. An adjustable wrench is designed to grip flat surfaces, not round ones. It will slip on the filter's curved body and can damage the filter or your hands. An oil filter wrench is the right tool for this job.
What size Harbor Freight oil filter wrench do I need?
Check your owner's manual or look at the old filter you're removing — the diameter is printed on the side. Common sizes are 2.625, 3, and 3.625 inches. If you buy an adjustable band wrench, size doesn't matter as much because it fits multiple sizes. If you buy a socket wrench, you need the exact size.
Why does my Harbor Freight oil filter wrench keep slipping?
The strap isn't tight enough, or the wrench is the wrong size for your filter. Tighten the handle firmly before turning. If it still slips, try a different size or upgrade to a socket-style wrench, which grips tighter. Cheap band wrenches slip more often than mid-range ones.
Can I use an oil filter wrench on a cartridge filter?
No. Cartridge filters screw into a housing on top of the engine and require a cartridge wrench with a center hole. A band or socket wrench won't fit or grip properly. Check your owner's manual to confirm which type your car has.
Do I need to replace my oil filter wrench if it gets damaged?
If the strap tears or the handle breaks, yes. A damaged wrench can slip and round off the filter. Harbor Freight wrenches are inexpensive enough that replacing a damaged one is cheaper than dealing with a stuck filter later.