Z4 M54

[2one3E90]

Hi guys, its almost summer in california and is it okay to use a 20 coolant / 80 distilled water mix?

[Clearancediver]

No… use the proper ratio. What your are proposing will lower the temperature at which the car coolant will begin to boil over…… the opposition of which you think you are going to accomplish.

[itsjustascratch21]

If your topping up with that, you'll be fine. Tap water is fine too, adding coolant for a top up is overkill.

If you're performing a drain and fill 80/20 is probably okay depending on how much coolant you have on hand. I wouldn't worry about it too much water under pressure has good heat capacitance.
The heater core hoses and o-rings take a beating in the summer if you run the air conditioning in traffic.

[Clearancediver]

You should read up on the properties of coolants and proper ratios…

[pungo]

Originally Posted by itsjustascratch21

If your topping up with that, you'll be fine. Tap water is fine too, adding coolant for a top up is overkill.

If you're performing a drain and fill 80/20 is probably okay depending on how much coolant you have on hand. I wouldn't worry about it too much water under pressure has good heat capacitance.
The heater core hoses and o-rings take a beating in the summer if you run the air conditioning in traffic.

I do not recommend this, especially using "tap water".
Use a 50/50 mix of coolant/distilled water, no matter where you live, no matter the time of the year. There's way more properties to antifreeze than simply preventing freezing, fact...