mctga said:
A car wheel bolt torque value is based on the friction of a dry thread. Greasing the thread reduces the friction therefore over tensioning the bolt, which will elongate it and potentially result in failure. Basic mechanics. There was a photo posted on here a while back by marco of a failed bolt.
I've done a thread on lubricating threaded fixings a while ago. Mctga is right.
For that reason, if a technician in the aerospace or railway industries was to grease a nut or bolt, they would be sacked because it's a safety critical incident. Think about that when you're flying at 36000 feet at 570mph or doing 186mph in a 800 tonne Eurostar. In comparison, some automotive "technicians" are thick.
There are some "pastes" used for dissimilar metals, thread locking etc BUT THEY ARE NOT LUBRICANTS and come with instructions on how to prepare the threads and adjust the torque setting.
I'll see if I can find my thread.
Paul