Only after I conducted tests on my engine's system have I found that the "orange" coolant appears better than then the ethyl-glycol coolant. I found that even if you want to replace the coolant annually; the orange coolant produced less harmful impurities than the ethyl mix. There may not be any need to change your coolant, but the worst problem with coolant-heating systems is the deterioration of the aluminum material in the coolant path. This includes the heat exchanger in the cabin, and the tubing slots in the radiator. After one year of operation with the "orange" coolant is showed minimal deterioration.
If you are satisfied withe the ethyl-glycol mix there is no reason that you should "have-to" change over, but be aware that there is a difference in performance. I am going to stay with the orange mix in my system, and I include two bottles of pre mix in the back for emergencies.
