Hydraulic Q's

[tman1986]

Hey i just got my first excavator and i have a couple question's about the hydraulic system that hopeully someone here will be able to help me out with

1. is it possible to put too much oil in the system, is there suppose to be some air (as cylinder volume isn't the same both ways) in the resevoir, for instance i put oil in with all cylinders while they where compressed, ran it, put more oil in with cylinder extended ran it, but notice drop in power and that my resevoir would actually move from im guessing pressure build up when the cyinders compressed, i allowed a bit of oil to come out the breather and power was increased but im not sure about what im doing here... any tips would be great

in other words how do i know when i have enough oil in my hydrualic system

2.whats the proper way to use the breather on my resevoir i know what it does but what is it's purpose, is it simply for relieving pressure for opening the system, or is it vital in the proper function of the machine while it's running
again any tips would be greatly appreciated

i may have some more Q's in the near future but i figured i would start here as ive read through many many forums and threads but could not find specific answers to these questions

The machine im talking about is the rc4wd earth digger btw i was sceptical about purchasing it cause it's from china i thought the quality wouldn't be up to par with other models but i must say every aspect of this machine greatly exceeded my expectations, i haven't seen much written about it by anyone who bought one here or anywhere for that matter so if anyone has any Q's about it i would be more then happy to answer

just a bit about it,
i was told i got version 1.5 it's valve block is different from most i've seen it's 3 spool but has 4 servos one is switch operated to relieve some pressure in the system along with the main pump switch make's it seem pretty efficient, one way for show and moving the boom around almost zero strain on motor, flip the switch and full power through the pressure valve for digging, i thought that was neat and unexpected, sorry i had to mention it

Thanks for any and all replies
Trevor