Reply to "Oil Pan"

This raises the question to me if 9 quarts is really needed?

I do know that I have 12 quarts in the system of my Cleveland using an Aviaid pan, a dual filter, about 10 feet of -10 hose and a 6" x 12" x 1" oil cooler, the automatic auxiliary fan for the oil cooler has never come on.

It takes a while for the oil to get hot as well.
You could change that variable by running less oil in the system overall.
Clevelands much like FE's have shown some circumstantial evidence of oiling starvation due to lack of oil in the pan under duress. I haven't heard that suggested about W blocks but they do have a different oiling priority.

Now not having a W pan here to compare it to the C pan, I don't know why it would have a -2 qt difference necessarily?

You might have to look at the differences in height from the pan bottom to the block pan rails C vs. W?

I don't have any W pans here to check that dimension for you but Aviaid does show exterior dimensions of the pans that they offer.

Maybe that would help? The height would seem to be the only available variable between the two to me and that likely would change the quantity of oil the pan could hold.