Yes the hole I'm talking about is called "Lubriwell" by Oregon however I have rarley seen the 72/73/75 LGX series with the lubriwell feature on it. I more commonly see it on 3/8 Stihl branded chains but do not know what they call. it. Either way stock/OEM Oregon bars may last through 5 chains but my Totals can get me through many more... Steel quality is the main factor and I don't personally use Oregon bars now b/c I feel they have inferior steel when compared with Total/GB/Stihl/Windsor bars. Bars also need to be properly filed, greased, and maintained at least once a year but most people don't bother with it. The OP will have to decide how much chain he uses and wheather it's worth it for him. I have more than 12x 100' rolls on the shelf here to feed friends needs (mostly oregon/carlton chain bought at auctions). Which brings me to another point... If you run into chainsaw bars at auctions or pawn shops that will fit your saw (or can be lightly modified to fit) chances are you may have a different DL count and may need to lengthen or shorten several chains you already have. Done this a ton since I got all this chain.Not too far, how many stock echo 670 bars would be needed to use up 100 feet of chain assuming you didn't hit rocks wire etc more than 25% of the loops. I know needed is relative and there are other variables I just seem to recall 5 loops per bar somewhere until control becomes less.
I believe the capilary hole as you call it is trade marked lubriwell by Oregon and is one of the differences between many commonly used sizes chain vs Carlton.
And if we are going to hit all the points here; you might need to determine how many years you actully plan to be cutting firewood. I don't plan to be doing it much past 65yr/old at most. That's 34 years from now for me...