Changing the oil yourself only takes about 30 minutes. But nothing can put the brakes on that quicker than a stripped, rounded drain plug. If you can’t get the drain plug out to drain the old oil, you are stuck until you can find a solution.
Learn how to remove stripped, stubborn plugs before you get to the point of dripping oil and potential engine damage. A little threaded plug should not be the reason that interrupts an efficient oil change.
How Does an Oil Drain Plug Get Stripped?
The term “stripped” oil drain plug (or oil pan plug) is typically used to describe a condition in one of two instances. These conditions are contextually distinct and can be repaired in different ways.
The first condition, described as a “stripped drain plug,” involves damage to the threads of the oil pan drain hole, which prevents a drain plug (or oil pan bolt) from being torqued properly.
This condition often leads to ongoing oil leaks and should be repaired at your earliest opportunity. If issues such as these are not repaired, combustion engine failure may occur at the hands of insufficient oil levels.
Stripping of a drain plug or oil pan’s threads typically occurs as the result of over-tightening.
All drain plugs have a specific torque that they should be set at when the drain plug is reinstalled. If torque is ignored and over-tightening occurs, the threads of a drain plug or oil pan can become stripped, which will render the drain plug useless.
The second condition, often referred to as a “stripped drain plug” generally refers to the rounding-off of the drain plug’s shape. Thus in such an event, a wrench or socket is unable to be applied properly to a drain plug when attempting to remove it.
In such cases, there is no possible way to drain old oil from the engine’s crankcase. Ultimately, the condition must be corrected before an oil change can proceed.
The most common reason for a drain plug’s head to strip or round off is that an inappropriate size socket or wrench was used during the previous removal/installation process. For example, this often occurs when a socket is a standard size and the drain plug is a metric size, and vice versa.
Once a drain plug head begins to strip or round-off, it is all but guaranteed that it will strip/round off more and more with successive oil changes.
How to Remove a Stripped (or Rounded) Oil Drain Plug
As we mentioned before, the term “stripped drain plug” refers to two separate situations. The procedures to remedy each of these problems are not the same, but with a cautious approach, you should be able to handle either situation.
Drain Plug With Stripped Threads
Drain plugs with stripped threads often can be removed by simply turning the plug counterclockwise, either by using a wrench or a socket wrench. You may need to push slightly outward on the plug itself to get the threads to engage fully.
This should not be a problem if you have a flathead screwdriver and a bit of persistence, as you can insert the blade of the screwdriver between the outer surface of the oil pan and the bottom of the drain plug’s head.
If the head of the stripped drain plug is flush to the body of the engine’s oil pan, you can simply rotate the plug counterclockwise with channel-lock plumbing pliers and apply outward pressure to remove the plug.
In either case, this method should work for most situations, even if conditions are not ideal.
Drain Plug With Rounded Off Head
Removing a drain plug is a different matter if the drain plug head is simply rounded off. A rounded drain plug head usually means you have to resort to a specialty socket called a bolt extractor.
A bolt extractor is a lot like a standard socket in that it fits onto the head of a bolt, but has spiraled internal grooves that help latch onto the head of a rounded-off bolt.
Irwin Tools makes one of the better sets, and it is very affordable. With a bolt extractor, simply tap it onto the head of the drain plug with a dead blow hammer.
The internal grooves in the bolt extractor will bite into the head of a rounded-off bolt, which greatly simplifies the removal of that bolt.
How to Fix a Stripped Oil Pan Drain Hole
There are times when the drain hole on an oil pan can become stripped and make it impossible to correctly torque your drain plug. This can be very disheartening and cause much distress among many car owners.
However, the issue can often be easily remedied using a good oil drain plug repair kit from Lisle or Super crazy Tools.
Oil drain plug repair kits are best designed to remove all damaged threads remaining in the drain hole of the oil pan, and then rethread the drain hole to accept a new, slightly oversized plug, which is also used on oversized drain holes.
If executed properly, which is why a quality kit is recommended, the replacement drain plug will be installed the same way a new OE plug would have been. This process can save time and the hassle of replacing an oil pan entirely, and you will avoid paying a hefty price for a new oil pan, too.
How to Use an Oil Drain Plug Repair Kit
The steps below explain, in a general sense, how to use an oil drain plug repair kit.
#1. Remove Damaged Threads.
Most oil drain plug repair kits contain a reaming bit that removes any remnants of previously existing threads so you can obtain a clean surface to tap for a new drain plug.
#2. Tap New Threads.
Next, a specially sized tap is carefully threaded into the drain hole of the oil pan. Turning the tap cuts new threads for an oversized drain plug to grab.
Taps such as this are usually turned a few turns in one direction, and then 1-2 turns in the other direction, while being threaded deeper into the depth of the oil pan’s drain hole.
This sequence is repeated until the tap is threaded through the full depth of the drain hole of the oil pan.
#3. Inspect Threads.
Once the drill and new threads have been created in the drain hole of the oil pan, it is advisable to inspect your work. Make sure that all threads have cut face-to-face evenly, and that there are no metal shavings remaining.
#4. Flush Out Oil Pan.
After you have successfully tapped new threads in your oil pan’s drain hole, it is common practice to flush a ½ quart of oil through your vehicle’s engine before you install a new drain plug.
This will remove most of the metal shavings so that they’re not recirculated, moving throughout your engine’s oil.
#5. Install Oversized Drain Plug.
At this point, you will now install a new drain plug in your oil drain hole that has the new threads from the tapping procedure. You will want to be moderately careful while tightening your new drain plug during installation, to discover anything abnormal that may arise.
The drain plug should be torqued to whatever specified value your repair kit instructions indicate. Afterwards, inspect the sealing washer to see if it’s seated evenly around the outer edge of the drain hole.
#6. Refill Oil and Check For Leaks.
To verify the integrity of your repair, check for leakage once you refill your engine crankcase to capacity the fresh oil. If no leakage is visible, start the engine and check again for leakage.
This check should be done again after you drive your vehicle for a very short distance. If your oil pan and new drain plug both appear to be dry after a short test drive, you likely do not have anything to worry about.
Preventing Stripped Drain Plug Threads
Although it is impossible to guarantee you won’t encounter drain plug damage that could be attributed to a vehicle’s prior owner, you can take measures to help prevent inflicting damage yourself.
By strictly adhering to the following procedures, the potential for stripping a drain plug is virtually eliminated.
The first of these measures is to use the properly sized wrench or socket when performing every specific oil change.
By making sure to use the appropriately sized wrench or socket, you greatly reduce the chance of rounding off the hexagonal shape of the drain plug. Information relative to the drain plug size for a particular vehicle is often available via the Internet or by referencing a factory-specific service manual.
It is also recommended to adhere to appropriate torque specifications when tightening a drain plug. This makes it less likely for the threads of your engine’s drain plug or oil pan to get damaged.
Using a torque wrench not only can help standardize and prevent any over-torquing, but also prevent leaving a drain plug in any state that would be considered loose.