They just want to avoid liability when you build your motor and it comes apart, and the lawyer claims the torque wrench was not accurate enough.
I counted 13 warning signs on a dumpster the other day!
Do not worry, use it on everything. But first, find a friend with an expensive torque wrench and compare them at 75 and 100 ft-lbs. Then you can offset it a few pounds if it really is off by 4%.
Using a torque wrench on tires does not make it inaccurate. But dropping it on the floor will
My Craftsman torque wrench is almost 40 years old, and it was within 2 ft-lbs at 100 ft-lbs when I checked it last year.