Welcome to the board
. Let's get the first thing out of the way; it is customary to post pictures of your car as a newcomer to the board
Let's see that '73T you have. We enjoy pics of P-cars.
As for best oil? I'm no expert by far, so I would simply say a good quality dinosaur oil 20W50. I use PennZoil for whatever that's worth. The search button on the top right is very usefull, you'll notice that this topic has been widely covered and good information can be found there. Cheers