Which is better for longevity and fuel mileage? Also I have a p pump and I know that a quart of my oil is used for lubing the pump but is it still beneficial to use a lubricant fuel additive. Can anyone help?

 

You're basically talking about two different sets of properties.
The two stoke will only add lubricity while the PS will add lubricity, clean your injectors, boost the cetane and add anti-gel properties.
My feeling is just the PS all you need especially with a P pump.

 

my rule of thumb, if its not designed for my truck, it doesnt go in the truck

I use power service because thats what its made for and 2 stroke oil is for motorcycles and lawn mowers

of course you could still use it but PS does a much better job

 

Do you mean I can use PS in my motorcycles and lawn mowers ?

Sorry I couldn't resist...

 

PS is all that I see you needing! 24V trucks with VP44's and CP3's need to run a little 2 Cycle for the lubrication with the new ULSD- - - - - All in my opinion! JB

 

I use 8oz of PS and 8 oz of 2stroke per tank. Get the cetane/inj cleaner and extra lubricity to boot.