C230 coolant puzzler
 

So I am changing the coolant. And I studied up on this quite a bit. I drained from the radiator drain and from the engine block drain. I attached hoses to both and collected all the spent coolant. I collected 6 quarts. However the manual says the capacity is 10 quarts. Is there another gallon in there? I have the thermostat off also since I am changing that. How do I get the rest of the coolant out? Fast answers appreciated since the sun is going down in 1 hour.

Thanks

Fill with fresh water, run engine hot enough to circulate water and drain again. You will now have 1 gallon of residual fresh water in system. Compensate when adding coolant.