so a week ago I did a flush and fill following the accepted procedure here on the forum using the mb approved zerex coolant , I added two gallons of 50/50 mix , brought the engine temperature up to normal and then topped the coolant bottle off with half a gallon of distilled water, everything checked out fine , coolant was at -34 degrees Fahrenheit , I checked it again yesterday and now it is only at -7 degrees Fahrenheit. with all of that my question is if I drain the coolant tank and refill with straight antifreeze should that be enough to bring it back to -34 and should I add a cooling system conditioner ? thanks in advance .

 

I would not add a damn thing, myself. Instead, I change the coolant every 3 years or so, no attention given to miles.

I can't do the math for how much it would take to lower the coolant to -34 and thinking about it, I do NOT think the relationship is all that linear anyway.

I'd let the car sit and get cold, suck out maybe 1-2 quarts and add 100% antifreeze, run the car and then test it again.

 

I think you had two things working against you. First I would say that you did not get all the water out of the block, even if you pull the plug. Then you added more straight water to the coolant reservoir. Once everything was well mixed you had less than 50/50. My suggestion is always that you only use 50/50 for topping off the system.

Always find out the capacity of a cooling system before starting. Then when refilling, fill half the amount with 100% antifreeze, then top off with water. Then I use a 50/50 mix for the reservoir.

James

 

thanks. I will make the appropriate adjustment to the system with straight antifreeze.

 

James really nailed it, if you ONLY add 50/50 at every time you add (or replace) ANY quantity, then if you started with 50/50, you will always have 50/50.

 

It is time for me to change mine (not going to do a flush, going to change coolant more often instead). So, um, where IS our drain plug? I have not even looked for it... Bottom of radiator as usual?

 

Yep, driver's side.

 

What do I do with used coolant? Motor oil is easy but coolant?

 

Save it and feed it to your cats. ( I'm a dog person )

Seriously, use this and enter your zip :
How to Recycle Automotive Fluids - Earth911.com

 

I took mine to Advanced Auto Parts for recycle.

 

This is a good overview of the steps for changing our coolant

 

GOt it saved, thanks Gary.

So the first step is to order the thermostat...

 

YUP, and when you are finished it should read -35 degrees. Did mine last Sunday. Following that
tutorial was great. At first I thought I had done something wrong, as the color of this Zerex G-05
is almost clear.
Billto

 

Remember 50/50 is a recommendation. If you are never going to see below 0 temps, don't worry about it. If you live in northern Canada/Alaska, and will see extreme temps, you need to go to 60/40 or even 80/20 to get protection for -60 or so. I live in Pittsburgh, and below zero is rare, but we have hit about -22F that I know of. If you live in Las Vegas, and never freezes, you still want at least 30% for corrosion and lubrication properties, and maybe some "water wetter" for cooling.