I was thinking about buying an inexpensive DYI a/c recharge kit and charging a/c in my Odyssey 2008 whenever the air it blows is no longer cold (once in couple of years; but I have 2 other cars). But then I saw some videos on YouTube, such as from Scotty Kilmer, that strongly discourage DYI. The arguments: (1) one gauge is not enough, because it measures only low pressure, but you need to measure the high one (2) you don't know how much refrigerant you put in, while the amount needs to be very precise. (3) it's important to vacuum off the old refrigerant and avoid any moisture in the system, while even the initial air in the hose of the inexpensive kit is already too much.
On the other hand, I see plenty of kits with one gauge from many manufacturers sold in all kinds of stores, and they mostly have very good reviews.
Can somebody advise: Is DYI OK to begin with? is it OK to just add rather than fully evacuate and recharge? Is it OK to use refrigerant with added "stop-leak" additives?

 

you cant spoil a rotten egg, Get a ac recharge kit, and see what happens, your not going to blow it up, and if you do, it didnt work anyway