Scotty, I have a 2015 Honda Accord (used)with 74k miles on it, the anti freeze is running a bit low. I was told to not fill it up to the fill line since antifreeze expands. Plus the antifreeze that’s in there isn’t the color it’s supposed to be. Is it wise to mix different brands of antifreeze?
First, … your coolant should be filled up to the top of the radiator, … plus just about 1/2 way in the expansion tank - that white, opaque tank with Lo and Hi marks on it that is connected to a radiator filler neck with a rubber tubing. You should be checking coolant level in the expansion tank when your car is cold and again when your car is hot. Proper level is if level in the expansion tank is somewhat about above Lo mark when car is cold, … and somewhat below Hi mark when the car is hot. That’s your expansion volume - differential between high and low actual levels.
Second, … best thing is to have good quality, long life, coolant in your system that is 50% concentrate and 50% distilled water - by volume. Honda coolant is recommended by Honda, of course, but good quality long life coolant by major brand formulated for “Asian” vehicle is OK.
Third, … yes you can just use a 50/50 premixed coolant to fill your cooling system, … but remember, when you changing coolant, you most likely use tap water to flush it out clean, first, … than you use a distilled water to flush hard tap water out, … than you drain it all out! Problem, however, is that cooling system actually can not be drained completely, and so there is a significant amount of distilled water in there - trapped! And, now, if you pour 50/50 mix to the radiator, you will end up diluting that 50/50 premixed coolant to something less than 50% antifreeze. Will that be significant dilution? It’s tough to tell, … and so, I will just tell you what I do instead:
I find out what is a total capacity of my cooling system, … than I divide that by 2. Next I pour that 1/2 of volume of full concentrate into the radiator, … than I top up the rest with distilled water. Mission accomplished, … sort of. Than, I warm up the car, … check level, … top up expansion tank with distilled water if needed. Done, …
F.S.
… btw, after a day or two of driving I check again system’s level, … and I check the concentration of the coolant with a hydrometer - a very cheap tester that you can pick up at any auto parts store! After all, … lowest temperature we recorded in my end of the woods is -34 deg. C, so I have to be damn sure that I have at least 50/50 mixture in there!
If the antifreeze is the wrong color for your Honda, now would be a good time to have a drain and re-fill with the right stuff = 74 K miles is a good time to do that, and antifreeze is a lot cheaper than a radiator or clogged heater core.
BTW Water expands when it freezes - ANTI-freeze shouldn't freeze, so that shouldn't be a problem.
It's not recommended to mix different types of coolants. The following comes from your owners manual, page 505.
NOTICE
If temperatures consistently below −22°F (−30°C) are expected, the coolant mixture should be changed to a higher concentration. Consult a dealer for more information.
If Honda antifreeze/coolant is not available, you may use another major brand non-silicate coolant as a temporary replacement. Check that it is a high quality coolant recommended for aluminum engines.
Continued use of any non-Honda coolant can result in corrosion, causing the cooling system to malfunction or fail. Have the cooling system flushed and refilled with Honda antifreeze/coolant as soon as possible.
Do not add rust inhibitors or other additives to your vehicle's cooling system. They may not be compatible with the coolant or with the engine components.
Pretty vague, isn't it. Here's a link for the Honda OEM Coolant.
Some of the ninth gens came with low coolant from factory. Are you check the radiator or reservoir tank?
Coolant doesn't need to be changed at 75k miles, honda type 2 can go longer than that.
