An over-tightened fastener is already half-broken.for lack of a spec, "grunt" usually works, but lacking that you can look in a Machinery's Handbook or other reference book for the typical spec based on hardware grade, size and thread pitch.
but lacking that good and snug with a 3/8 ratchet should suffice.
trust me your local mechanic isn't torquing them, he is doing them by feel.
only if you have exceeded the elastic limits of the fastener, and once you do that you are pretty close to the yield point anyway.An over-tightened fastener is already half-broken.
LOOKING FOR THE TORQUE ON THE REAR DRIVE SHAFT NUTS ON MY 2009 RAV4. THANKS IN ADVANCE.....