[dataway]

With the laser ... start by pointing it at an interior wall in your house to see if it agrees with your house thermostat. That would at least tell you how accurate it is in the lower temperature range. That would probably be enough ... because engine temps would still qualify as "low" temperature range for most laser thermometers.

I wouldn't use upper radiator hose, depending on the thermostat position it may not even have water flowing in it.

I'd guess you have an electric gauge ... the mechanical type are rarely off that far. But you know, never say never.