When assessing the need for an oil plug or pan repair, we often offer to show the customer the situation in the shop. One time the customer wanted to pop the plug loose himself as he cussed a little. We let him, and he got a big grin on his face as it popped loose. At that point he was OK with us moving forward with the repair.
Some customers want to go back to the previous oil change shop and have them fix the damage. I can say that nearly every time we have fixed the problem by simply chasing the threads and using a new drain plug. I can think of about five times in 10 years where we needed to replace a sheet metal drain pan and this happens mostly on older Hondas. In one case with an expensive aluminum pan we removed the pan, welded the aluminum back up and redrilled and threaded a new hole.
In another case we acquired a used oil pan from a salvage yard. Due to issues with keeping the hole centered, we don’t recommend trying to cut bigger threads in place. That technique also weakens the surrounding material. In the case where the drain plug head is rounded off and we cannot loosen it with a vise grip, we will simply weld a nut to the head of the plug and wrench it off that way.
As Overland Park’s go-to source for auto repair, we always replace the drain plug washer during an oil change. We stock 30 different styles of aluminum and copper washers and o-rings for the newer models. Our policy also states the drain plug can only be tightened by hand and not with an air or electric tool. (My guess is that most quick-oil-change places don’t abide by that rule.) We also rinse off the oil mess from the filter and the drain plug.
With these policies in place I can gratefully say we have never had to replace an engine due to a leaking oil drain plug we created. Our policies work!