I bought a extended 2012 E350 with 5.4 liter engine with 58K miles on it. I want to drain, flush, & refill with coolant so I end up with a 50/50% mix of coolant and water. Only when I drain the system, about 1/2 of the coolant will not drain. How do I now add anti-freeze so I end up with a 50% mix?
Are there additional drains on the block and drains for the rear heater? Any suggestions are welcome.