A co-worker was asking me what to do with an old propane tank that was coming up to it's "due date". It had the old valve with no external R/H threads and no OPD. I told him that I have gone from waiting for a gas station attendant to just doing the exchange at Home Depot. Now, the last time I went to the service station the only guy in the store said, "You'll have to wait 30 minutes for [other employee] to get back from lunch". I was not only furious but I really let the kid know that I am a customer and I do not have to wait for anything. If you can't sell it now, then you will not sell it at all. I promptly went to HD and paid a little more for the exchange, but I received a full tank and was on my way in a matter of minutes. I've been doing it since.. My co-worker cannot get over the fact that he will not get HIS tank back. I cannot convince him that a tank is a tank.. He definitely has no experience with welding gasses and the like..