I have a 2010 Mercedes E350 4matic. I got a message saying coolant level low. I added about a quart and a half worth of concentrated antifreeze. Do I need to take out some and add water? or is it ok.
You should have added a 50/50 premix antifreeze.
Test the coolant using a hydrometer tester:
Always use 50/50 coolant. 1 quart probably isn't going to hurt anything on a system with around 4 gallons of antifreeze. You may want to check out the cooling system in your Mercedes and see if it's seeping somewhere. The coolant shouldn't go down, so this is a pretty good heads up that something's not quite right. If you haven't seen any signs of leakage, I'd replace the radiator cap. They're cheap and will allow water to evaporate when they get old. I'd also rent a pressure tester for the cooling system and put the system under pressure for 10-15 minutes and see if the pressure goes down noticeably. If it does there's a leak.
This model takes 10.7 quarts, not 4 gallons.
Interesting. I guess what I read in Google was wrong