[BillA]

DIY on the cheap
I do suspect that had you spent some money to cal your temp system you would have told them to pound salt (as you did) w/o a worry
- so the site owners had no commitment, not your fault

some measurements will vary (the temp differential depending on measurement method), others should be very close (flow, pressure, air/coolant temps) depending on the calibration

a tester using uncalibrated equipment is in a poor position to assert much