[jb92563]

Yes the oil has to reach the right temp for optimum lubrication but just as important is that the entire engine block and head have to reach normal temps so that the clearances are in their normal operating range before you push it.

When an engine is cold, the clearances are tighter and the cold oil does not penetrate and flow quite as well through the tighter clearances.

I doubt anyone is damaging the engine if you occasionally overdo it while cold, but there will be more wear and tear if you do it on a regular basis.

5 minutes is adequate except perhaps in very frigid conditions.

An Oil Pressure guage is the most valuable instrument in my opinion because you know immediately whether oil is flowing through the engine properly.

With Oil Temp guage you may have NO oil flowing (Blocked passages) and you would not know it until the coolant started over heating..

The first 5 seconds after engine startup is the most important in terms of wear and tear.