15/50 is hard on the oil pump drive, I already worked on one that stripped the drive rod (motor was done after that)

I only drive my TBird to weekend car shows and on an occasional Sunday cruise.  My 292 engine had a complete rebuild about 3,000 miles ago.   I had all the traditional Y-Block oil leaks.  Try as I might, I still had to add a little oil every few months. Since I ditched the down draft tube and installed a PCV system, the oil leaks stopped and I have not had to add oil. 

When I changed oil in my 312 this spring I decided to try a synthetic blend along with adding a small bottle of zinc additive.  I apologize for not using a mechanical pressure gauge instead of the factory stock electrical gauge but I did notice no difference in pressure when cruising. At idle, I do have a slightly higher pressure than I did with conventional mineral based 10W30.  No leaks and not enough miles yet to determine oil consumption, if any. I was prepared to drain it out should there have been any negative effects but so far there are none. I used Motorcraft 10W30 synthetic blend and as always, a small bottle of ZDDP oil supplement.  Dry Lakes Racer, good comments regarding your Coyote 5.0   I would trade a a quart of oil every several thousand miles for a couple more MPG any day - great enegine.

64F100 57FAIRLANE500