This post is full of excellent information. However, it's about oil, not NOS, not fuel, not water. The viscosity of oil is heaver than all of the above. Fittings do indeed create flow problems.
Two purposes of oil:
1. Create seperation between two parts
2. Transfer temperature away from metal
Fittings-
-8 45 degree ell has the resistance of 8 feet of straight line
-8 90 long radius ell has the resistance of 10 feet of straight line
-8 90 std radius ell has the resistance of 15 feet of straight line
-8 180 ell has the resistance of 25 feet of straight line
If you have ever seen the oil schematic of an engine, you would wonder how the oil can even do its job. The pressure path is unbelieveably complex. Oil restricters, additional side plumbing on the side of the block (force feeds every main bearing), polishing and blending any passages and the use of accumilaters are insurance for the life span of your engine.
Too little pressure and you have failure. Too much pressure and you have failure.
Phew, sorry! I'll go back to bed now....
Dave