Its coming close to that time to do the initial start up and break in on my 68 gto 400 h.o. motor. I know there are many different ways people go about this. Im looking for opinions. In the past I would take the car out, vary the rpms for and hour at a time but staying under 50 mph for approx. 300 miles. I then change oil and open filter to check for metal. I don't use any break in oil. Looking for opinions.