One of the most routine parts of car maintenance is changing your engine oil. Back in the old days, manufacturers recommended changing it every 3,000 miles. Now it’s every 5,000, or every 7,000, depending on the vehicle. And with some high-grade synthetic oils, you can even go 10,000 miles or more between changes.
Regardless, you’ll have to change your oil sooner or later. Normally, it’s a simple, straightforward job. With a socket wrench, an oil pan, and 30 minutes of time, anyone can change their own oil.
At least, that’s what we all hope. In practice, Murphy’s Law sometimes kicks in, and you can end up with a real mess on your hands. One of the most common issues people run into is a stripped oil drain plug. If you can’t get the plug out, you can’t drain your oil, so no oil change is possible. Moreover, a stripped drain plug might not go in correctly once it’s been removed. This can lead to a slow oil leak, which is bad for your car, your budget, and the environment.
Thankfully, fixing a stripped oil drain plug isn’t as difficult as it might sound. Here’s a complete guide to the process.
What Happens When an Oil Drain Plug Gets Stripped?
When people talk about a stripped oil drain plug, the term “stripped” can mean two different things. First, the head of the drain plug might be damaged. When the corners of the plug’s hex head wear down, it can eventually become impossible to use a socket wrench on it. Suddenly, the drain plug becomes much harder to remove.
In most cases, this happens because a mechanic used the wrong sized socket during an oil change. Metric and standard-sized plugs are close enough that these mix-ups do occur. And once the corners start to get rounded, each subsequent oil change will only worsen the damage.
The second way a drain plug can get stripped is if there’s damage to the threads on the side of the plug, or the ones inside the drain hole on the oil pan.
This type of stripping normally happens as a result of the plug being over-torqued. All plugs have a specific torque rating, which you need to follow during installation. When the plug is screwed in beyond this torque level, the threads can get worn down, or even broken off completely.
When drain plugs have broken threads, this may leave an opening for oil to leak through. As a result, your car may develop a slow leak, and you’ll need to constantly top off your oil. And if you’re not paying attention, you might even lose enough oil to damage your engine.
Regardless of the type of stripping, you won’t be able to change your oil until it gets fixed. Let’s talk about how that’s done.
Removing a Stripped Oil Drain Plug
As we already discussed, a stripped oil drain plug can be stripped either on the head or on the threads, and different problems require different solutions. Here’s how to remove a stripped oil drain plug under both scenarios.
What if the Head Is Stripped?
If your oil drain plug has a stripped or rounded head, you’ll typically need a bolt extractor. This is a special socket, with internal grooves arranged in a reverse-threaded spiral.
Take your bolt extractor, and use a flat-headed hammer to pound it over the end of the drain plug. This will cause the internal spiral groove to dig into the head. When they’ve bitten in tightly enough, you can attach either a socket wrench handle or an impact driver to remove the plug.
Keep in mind that if the head is stripped due to over-torquing, the threads themselves may also be damaged. In that case, you may also need to continue with the next procedure.
What if the Threads Are Stripped?
If the threads are stripped, the plug can still be removed. However, the more badly-damaged the threads are, the more difficult it will be to get any surviving threads to engage.
If there’s a gap between the surface of the oil pan and the bottom of the plug’s head, insert a flathead screwdriver into the gap and pry it outwards as you turn the bolt. This outward pressure can help the threads to bite.
If there’s no gap, you’ll have to get more creative. You can use a pair of channel lock pliers to pull out on the plug as you turn it. In most cases, this will provide enough force. If it doesn’t, try using a penetrating lubricant to aid with the extraction. A heat-activated lubricant can be particularly helpful.