New thermostat

Just run it a while and rev it up a little and then carefully open the radiator cap to top it off a couple times. I say "carefully" because air trapped in the radiator will burp a bigger volume of hot antifreeze than does a liquid....hot air under pressure expands more than liquids. Keep the overflow bottle full as this tops it off every time the engine cools off sitting overnight. Air burps out...liquid is drawn back in when it cools.

Remove cap from overflow tank fill with antifreeze to full mark leave cap off and start vehicle and let idle you will notice level in tank start to rise this is normal once thermostat starts to open level in tank will drop add more antifreeze to full mark then put cap back on.