The break in instructions on my Roush 427IR (Dart 351W block) were to use petroleum based 10W30 for the first 500 miles, run it at highway speeds AFTER warmup, and do like Brent said - accelerate, decelerate a little. I did it by visiting on/off ramps on the freeway for about 300 miles. After that it was local driving (which in our area is NOT city start/stop). There was something about keeping it under 5K RPM (which is something like, what, 140 in 4th?) It was hard not to go above that when starting in 1st and 2nd though
Cobras are like real snakes - they like to strike fast
Then after the 500 mile change the
oil and filter, and after that you can use
synthetic. I use Mobile 1 10w30 and it runs great.