Good memories when i got let loose about 23 years ago in my own service van, i bought the equivalent gunsons easibleed from halfrauds and set about using it on forklifts and plant etc of the era with some good results being able to bleed up old knackered kit that had snidey poor master...
regular oil change with correct oil shouldnt get to a stage where a flush is considered .
i use best oil i can for my engine as it is best piece of mind for me doing all i can to prevent premature timing chain / turbo / cam lobe wear
looks like a carbon copy of my sealy vs820 i use on plant machinery
fits most screw on caps ive tried as most are the same
but i also have the universal adaptor if i get stuck say on a toyota with the flip off cap ( i used to do old avensis clutch bleed)
never used on my audi to be honest but it...
my old off grid shed solar panel with charge controller ( that has different battery type settings) to suit pb and leisure batteries trickle charges batteries into life well just like the charge controller on a camper
bit of further reading...
it be fine to use now mostly at least to get it to a state of charge to start the car! ---just not an optimum charge curve and may not get battery past 90% / or a bit over charge etc as it may be slightly confused logic when to cut out at its U vs A