Don't fill it up to the cap, you need the air for expansion..... If your full to the hot line then adding more won't help with cooling at all. Either you have faulty temp sensor or maybe a tstat issue, but you know what 160 ain't all that bad. Lol
Sorry but u are wrong.
I have proved it on over a dozen ctec sleds.
That additional 12oz make a huge difference.
Air and water both take up space. The cup is never half full or half empty..... its always full, with Water and air....
Coolant doesn't need to expand at 150° and if it did, the air that is in the bottle would have to push the cap open and leave to allow room for the water to expand....
I put 1,100 miles on my 18 and it stayed full to the cap the entire time.
My 19 has a leaky head and i still only add 2-3oz per month. Over flow tube is always dry.
Sent it