So let me get this straight.....
Some of you guys bought a "precision tool" at harbor freight?
One guy tested his and said it was 10 ft lbs off off at 20 lb torque...
Most bolts on an engine are low torque. Assuming you are using a cheap torque wrench, you may as well not be using one at all. Just "getting in the ballpark" isn't the purpose of a torque wrench, or torquing a bolt to spec in general.
Im not saying you have to spend $400 on a torque wrench, but I definitely wouldn't waste my time using a harbor freight if they are of the same quality as the rest of their products.
I personally have a snap on. Got a great deal on it and it has lasted. Its one of the few snap on tools I have so im not what you would call a snap on nut.