Gents:

I just had aluminum plates welded to my blade oil pan and the old drain plug welded shut--i.e., the Chris G modification. For the new drain hole, I planned on using a 3/8" tap because that is the biggest I have. I think the old drain plug was a 12 or 14mm. Do you think a smaller drain plug will cause problems? I don't see how it could, but wanted to ask you folks first. Also, is course or fine thread better?

--Thanks, Chris

Fine threads take more torque. Drain plug could be "tiny" as far as I can see. It will just take longer to drain the oil out.

I think a large one with a "magnetic" drain plug is a good idea to see what metalic gunk you have when draining the oil but that said see paragraph one.

Just my honest opinion though so could be crap!

As vince said. Size doesnt matter ( oooh err). Fine threads are best to get tighter and less likely to pull the thread.

I believe the usual practice is to use a courser thread into allumium becauce a fine thread is more likely to strip .Like every one else I agree that size does not matter but you will need to have a sealing washer on the bung.
best wishes
Iain

Thanks for the response gents. For the washer, should I look for a nylon washer or a stainless? Does it matter?

--Chris

waht you need is an soft / non deforming material in the conditions

wich are wet/ non biting / but at temp (90degrees lets calc 120)

then the best option is copper or alluminium..

TKs