is a 50/50 already mix antifreeze good for year round use.or would a concentrate be better.

Same protection, different price.
You spend less money for the same 50/50 mix when you buy the concentrate.
( add your own water and not pay them to do it for you nor pay for shipping water. )

You’d choose the premix if you don’t have a source of water and need antifreeze right now.
With the concentrate you can choose a stronger mix if your weather demands it

It really depends on where you live. The optimum coolant combination is a 50/50 mixture of antifreeze and water. The 50/50 mixture will produce freeze protection down to -34F (-36C), and boilover protection up 265F (129C). However, in colder climates, where lower temperature freeze protection is needed, a mixture of up to 70% antifreeze can be used. I used 70% anti-freeze in Alaska and Northern Maine where temperatures could get as low as 70 below zero.

If you need protection below -34F, follow missleman’s recommendation. Otherwise, if you buy concentrate, you still have to add enough water to make it a 50/50 mix, so it doesn’t matter which one you buy, as long as it gets added properly and diluted properly if necessary.

Since I don’t like to mess with distilled water, I just buy the premixed antifreeze/coolant.

I usually drain as much antifreeze as I can and set it out in marked jugs for our garbage. I then flush with a garden hose until it runs clear. It is never possible to get all the water out so I put the right amount of full strength in and fill with water. I then mix my own 50/50 for the overflow jug and topping off for the next few days.

If you don’t have access to distilled water or do not want to take a chance on your well water are considerations I would be in favor of 50/50. I have NEVER had a problem using tap water from well or city, but I change my coolant every 2 to 3 years if not “long life”. So to me, it might be a concern for longer change intervals. I use time, and not mileage for coolant change. I live in central Maine and have never had a problem with 50/50 but as suggested, would move to higher range in even colder climates. There is not enough summer heat in these regions to worry about over heating with up to 70% unless you tow. Then it could be a problem decision.

It’s interesting to note that Ethylene glycol is readily biodegradable in standard tests using sewage sludge. So it’s a hazardous waste, not because of it’s make up, but the heavy metals from use in coolant systems. I know at one time, CR said you could dump and bury standard coolant from a change (do not let pool as it’s poisonous} as long as you were sure there were no lead based solder connections in cooling systems. I doubt they make that statement anymore.