WHAT HAPPENS WHEN YOU MIX COOLANTS?
If you mix coolant colors, you can come across two different opinions. Some people do not see anything bad with it, as long as the type of coolant matches the one already in the system. However, according to experts, it is best not to mix different coolant colors – just for safety. For instance, there are some combinations that can completely ruin your car. Mixing OAT and IAT coolants can be detrimental. What is OAT coolant doing when mixed with IAT is turning the auto coolant fluid into a gel that can clog the cooling system and cause the engine to overheat. Removing this paste will take a lot of flushing and even cause damage that costs more than you realise. The same can happen when mixing propylene glycol and organic acid.