I use "Z_TILT_ADJUST" in my Start GCODE:
;----------Proforge 3.5 Start G-code----------
G92 E0 ; Reset the extruder motor.
Z_TILT_ADJUST ; Level the 4 Z motors.
G0 F8000 X120 Y25 Z0.80; Move the nozzle to the front edge.
G1 F4000 X260 E20; Prime the nozzle.
; ----------Proforge 3.5 Start G-code----------
Does it adjust each Z-motor to make the bed level?
How close will it get the bed to level?
Is the adjustment persistent?
My understanding and observations are the following:
1) It will use all of the 4 z stepper motors to level the bed
2) In my case, the adjustment is persistent as long as the steppers are not turned off. After I shutdown the printer for some days, the next time I perform the z-tilt, I usually get a larger difference to correct. Therefore I also added a Z_TITL_ADJUST in my start g-code :-)
3) Here is a typical output I get on the console: