Is it bad to add anti-freeze to my car without mixing it with water?

[Anchorsmash]

I added coolant to my BMW 318Is without mixing it with water and was wondering if it can cause any harm to the car. My mechanic said it's better to add it without mixing it but i want to double check.

Thanks for any feedback

[3050rpm]

It depends on the type of coolant you were using, pre-mix or not. As the name implies, the pre-mix formulations are already set to pour into the system, the non- requires the addition of water. In your present circumstance, you're probably okay, but see below...

There are a few important things to bear in mind. First, use a modern formulated brand of coolant, I believe BMW requries one without borates, silicates, or phosphates. Second, optimal coolant performance comes with a 50-50 mixture, which is something you don't have to worry about with the pre-mix types. Third, if you do add water, use distilled water, not tap. Fourth, if you haven't done it in the past three years, you should thoroughly flush your cooling system, meaning radiator AND engine block, and put in new stuff.

[Manolito]

3050rpm's advice was excellent. I would add a couple of notes:
1) I presume you added only a pint or two, so if anything, you most likely brought a typically over-lean coolant mix closer to 50:50. You certainly did no damage.

2) Speaking from the bitter experiences of myself and others who have posted, it is best to bite the bullet and use BMW branded coolant. You can get it on line much cheaper than at the dealer. Avoid DexCool coolants.

[C Sean Watts]

Originally Posted by Manolito

Avoid DexCool coolants.

This can NOT be overstressed. I would add not just avoid it, DO NOT USE IT AT ALL!!

Damage photos

Lawsuit over dexcool damage

Settlement and more damage info.

[kevzep]

Also put the heat up full when you are filling the sytem. I'm not sure if this applies to aircon models but it cant hurt.