Hi,

Opening up the hole and retapping it for a larger bolt, if possible, will only take about a half hour or so... I would not expect to pay more than $100 at the absolute tops for this, realistically more like $50.
Further, you can usually purchase a tapping drain plug from most auto parts stores that have a taper on them and will solve this problem as well. They run about $10 and you just need to slowly install them and allow the taper to cut new threads. Very easy fix.

That being said, you can usually just re-tap the threads on these for the original thread size and install a new drain plug and be fine. I have honestly run into only a few of these that were stripped so badly that the pan required replacement (or modified with a taper bolts, etc).

It is a much better solution to replace the pan if it really is that bad that there is no other option but to make a larger hole and cut new threads. The worry here is that the threads are just being cut into a nut that is tack welded to the inside of the pan; the increased torque of trying to cut threads into this hardened steel nut will often break the welds and pop the nut loose... at which point you have no choice but to replace the pan, or remove it and weld in a new nut, as the wall of the oil pan is not thick enough to thread for a bolt without the nut welded on the back side.

Of course the problem with replacing the pan is it is very expensive... with around $200-300 for just the pan (depending on aftermarket or genuine parts), and another 4-5 hours in labor to replace it, it is quite the expense. Again you can nearly always just retap these for a stock plug or use a taper plug and it should take about a half hour.... not a couple hundred dollars by any means.


With regard to the oil burning, valve seals are extremely common on this engine and will consume oil at a good pace; repair is rather expensive (nearing $1000 depending on the shop doing the work). Oil leaks are also quite common and will result in significant oil loss. At 156k miles, both are probably creeping up on you, however each vehicle is different.... depending on the maintenance performed, these problems do not always appear, they are just fairly common to the model as you have been correctly informed already.


Personally, based on the "couple hundred dollars" to retap the drain plug, I would get the vehicle to another shop for a second opinion on this before authorizing any work. Unless the welded nut broke loose off the pan, I don't see any reason to charge this much money for re-tapping the drain pan, whether for the same size or larger, anything over $100 is way too much money for that job.