What will it do

[TomPob]

Just had a new rad fitted, and the thermostat is shot. At the moment it is fully open all the time. The engine is still running up to hot and needing the fans. But what damage would running the engine with the thermostat fully open all the time do. Should I just take longer warming it up. I'll be getting a new one, but need to use the car next week without it. Any advice?

[TomPob]

Used the car last week with the stat fully open. On the motorway I was running at about 65 degrees. Is that too low?

Tom