You want a 50/50 mixture. You can purchase it all ready mixed.
50-5050-50
Minimum 50/50. Maximum 70/30 (coolant/water).
The proper ratio depends on the temperatures your vehicle will be operated/stored in. Typically, a 50/50 ratio will be just fine. If you will park/store your vehicle in extremely cold (sub-zero) temperatures, you can increase to 60% coolant to 40% water.
50/50 for most application
The water pump circulates the coolant to cool the engine.
You need a 50/50 mixture of water and antifreeze.
IN THE WATER JACKET.
Usually 50 / 50 mix ( Ford states not to exceed 60 % antifreeze and preferably distilled water )
Any Ethylene Glycol based coolant mixed in a 1:1 ratio with water. Prediluted means it is already in the correct ratio.
50/50
To add coolant to and 1985 Mercedes 380se find the reservoir located in the engine bay next to the radiator. Make sure to use the proper mixture of coolant to water ratio and pour until the appropriate level. Overfilling can lead to sprouting a leak while the engine is running.
50% water to 50% coolant is the standard unless you live in a very cold climate where it goes down to -25 degrees F or lower, then you may want to mix 25% water to 75% coolant but never straight coolant.