Cam2 and VP your going be paying for the name as much as the oil.
Highline Warren owns Mag1 and they also own a ton of other lube n fluid companies, and most of them are big box store names. I’m not sure who Gard is as there are too many types with “gard” in their name and tag line. Either way I have not used any of them particularly VP n Cam2 since they are always pricy. IMO race gas companies are only selling bar oil as a money grab so ur going to pay for it.
Just about any farm n tractor store brand has worked for my uses and Walmart brand is absolutely terrible! I’m currently running husqvarna x-guard since I got 4 gallons for $48 and it’s been good.
Normally I use w/e is the cheapest and is thick enough to get through the pump but stay on the chain through the bottom of the bar. I’ve found thicker is always better, as you can thin it with a splash of kerosene or diesel. I’ve also thinned it with a cheap light weight motor oil. On top of that you need to remember it will thin out after the saw body heats up. It really depends on what wood you’re cutting and how long ur bar length is. IMO The average Joe homeowner-firewood cutter should get whatever is cheapest and works as they arnt using anything longer then a 24” bar. If your burning the bottom of the bar after a few logs then your not getting oil all the way around or ur chain is dull. The best way to buy bar oil is when your flavor is cheap/on sale, buy it. It doesn’t go bad and doesn’t really go down in price. Between my father n I we likely have 12-15 gallons on the shelf at any time and are always ready to buy it on the cheap.