Hello Everyone, so I decided to change the coolant on my 2006.5 Nissan 350z. The car has only 10K miles but the fluid is original so it's approaching 18 years old. I drained the old coolant but could only get about 1.5 gallons out even after putting the back up on lifts to point the nose down. I did a flush with distilled water and drained again but still only got about 1.5 gallons. Is this normal or do I need to do something else to get the rest of the old coolant out??? Thank you for any help!?!