What your post didn't detail is whether or not you are using a NEW crush washer each and every time. It will make the difference.
About 50% of the time (when the Honda parts guy remembered to throw one in the bag) I replaced the washer. I can't see how reusing a washer would effect the threads in any way. 29 FT-LBS is 29 FT-LBS on both a thin washer and a thick washer.
There are a variety of "temporary" rubber plugs that are 99% safe and effective. Just keep a watchful eye on the oil pressure warning light. If you go this route you must resist the temtation of twisting the plug once its released in the hole. It takes no more than 1/2 turn for the sharp edges of the threads to cut the plug. Failure will be eminent.
I've seen engine damage due to oil starvation, so any temporary solution, even if it is just used during the drive to the dealer, is unacceptable to me. I'm currently helping a friend rebuild his 13B rotary that seized after 1000KM due to the previous builder forgetting to properly set oil clearance. Spun every bearing in the engine, needed new stationary gears, eccentric shaft, front cover, oil pump/chain/gears, etc. Not a pretty sight. We had to disassemble it with pry bars and a torch.
Since the pan is magnesium welding is a very limited option.
Welding for me is not an option. While I'm sure there is a welder capable somewhere
in London, the cost is likely astronomical. I've had very bad experiences with welders before in that they like to charge a lot
for even the simplest jobs.
And a quality steel insert job is likely going to be some what costly and time intensive in that finding a skilled machinist to do the job will not be an easy task.
Nah...Bore the hole larger, then turn a piece slightly larger on a lathe. Drill, then tap the oil bolt hole. Heat up the oil pan in a tub of oil a few hundred degrees, put the sleeve in the freezer. Then quickly press in the sleeve. Less then $100 worth of work for my machinest (who I trust completely). Worst case is that an already damaged pan is broken more.
That's exactly what I was afraid might happen some day.
So I installed the FRAM Sure Drain Valve.
I intend to do this as soon as I have my new pan.
Another solution is to bore a hole through the existing oil drain bolt, tap the hole, then install a smaller in it. That way, you can remove/reinstall the smaller bolt without worrying about damaging the soft pan.
Yet another solution would have been for Honda to design it properly from the factory.
The "oil pan" is a rather complex casting. I could send you a 200k JPG blown apart view of the engine. What about using a helicoil insert? Any decent machine shop could do that.
Yes, there is quite a lot integrated into the pan. Filter, A/C compressor, etc. Also two large bolts that go through the IMA motor and into the transmission. It was a hard decision to send the car to the dealer to have it repaired. I have never
had anyone but me work on any of my cars, but I simply don't have the time to do this one by myself. Removal looks to be a good three hour process, then the cleaning of the pan and engine, then the reinstall. Probably 8 hours all told. Since I need the car this weekend (to head down to the shop and finish a rebuild on a 13B turbo rotary) I just can't have it sit in my driveway while I spend a few hours a day on it.
So basically, the car is currently at the dealer. They said they can get the part by tomorrow, so that at least minimizes downtime. But I can imagine that I'll certainly pay for the convenience.
I intend to take this issue up with Honda, since their design absolutely sucks. I would expect that this will be a common problem for Insight drivers very soon as the threads begin to wear. It is beyond me why a steel sleeve was not used in the factory, especially in a bolt that is so often removed, and considering how happy many mechanics are to use an impact gun on everything. As soon as the repair is completed, I will be calling Honda North America and voicing my concerns. This is the only problem I have ever had with the car, but it is a HUGE and EXPENSIVE consequence to such a stupid design.