Ran into this while doing an oil change, why is this like this? Why is there a chunk of thread missing? Vehicle is a 2019 Buick Cascada. Based on the look of things, At one point before it came to me the threads got cross-threaded or stripped, there was an attempt to retap and rethread the hole. There was a HeliCoil installed, And it came out while I was removing the drain plug.
I think it's just to allow for more of the spent oil to drain from the pan. Seen it on many different cars.
Edit: Keep in mind that not having a full set of threads makes the plug more sensitive to over torquing. Drain plugs do not require a lot of torque. Look up the specs for your car and use a torque wrench if you're uncertain.
So, you think this came from the factory like this?
Yes, I'm quite certain it did.
Interesting 🤔 I've seen some with drain holes in the threads, but this is the first one I've seen with such an excessive cutaway.