I would think the kicker is a specific GF-4 spec'd fluid and not a readily available GF-4/5 which Hyundai would recommend against due to GF-4 having the proper additive package and yellow metal protection. If the car has 150K miles on it and you're not looking at long term ownership it may not matter to you, but I'd always want to put the right product in it....which isn't always easy to find or easy on the wallet.