I will try again.
If you have a stock pan. (5 qt plus one for the filter) you actually have a 5 quart oil system
in the pan. The one in the filter remains in the filter at all times if you have a honest one quart
filter capacity.
If you had a 6 quart system it would be 6 plus one. The dip stick is calibrated to the fill mark
for 6 quarts (not 7 quarts).
If you install a 7 quart pan and run 6 quarts or even 5 quarts what you have done is lower the oil level in the pan vs the crankshaft. This may in some cases give you the 1 mph and .1 et change.
If you are drag racing and the engine showed good
durability with 5 quarts in the pan/engine during
the run, then running 5 quarts in a 7 quart pan
will work fine and may give you better performance
The issue comes in if you have a head that does not drain well during the run (stock Edelbrock)
and a oil pan that is not baffled properly. The
5 quarts may actually be 2 quarts in the heads,
and 3 quarts in the pan. This may be enough to cause oil starvation on some fast cars. Adding
the additional quart which the pan was designed for may keep you from wiping out bearings. Just
my opinion. Tom V.
