Never heard of that oil. Really unnecessary IMO because as soon as you begin cooking it's gonna "season" up :D But looking nice there. So did you build threads into those "bosses" for the rails with the JB Weld?
Opening the orifice will do NOTHING for your issue nor will messing with the shutter. I'm sorry as this may come off as a bit hard nosed. Number one, if you wanted a NG grill why did you buy an LP one?! Now to address the sizes of the orifice. Increasing that will ONLY cause the grill to over...
Trouble with FleaBay here is there are no checks and balances. Someone can a, not know the difference i.e. gas is gas mentality, b, tried to do what the original poster here did and "convert" and when it didn't work "ok" I'll simply sell it as such and such.
Honestly for something safety...
Buy it from a 3rd party IIRC GrillParts.com is one that sells parts and doesn't ask questions. I'm sure another of our members here will help me out on this and point you to a good source
Weber themselves will likely not sell it. Again their way of trying to force you to either A do something dumb or B buy yet another grill. I and the rest of us don't like being the barer of bad news but not gonna blow smoke up your butt and tell you it's brisket either.
There really is no good...
There is no "adjustment" and if you believe that I got some swamp land I can sell you. The issue is the valves not the orifices and without doing correctly the grill could actually become dangerous. Especially if you're trying to go to a lower heat. The burners can partially "flame out"...
Yeah IIRC someone actually compared them and found no difference. A burner is not what "decides" fuel type. It only burns what is properly metered into it.