The same power steering reservoir used on the Grenadier is on my ‘94 Porsche 968 (BMW & Porsche used the same supplier). For the first 30 years, no weeping, even with the original o-ring. And the low pressure return of the 968 can dump a huge amount of fluid all at once. So if the reservoir is weeping a lot, I’d be looking for a warped cap, a poor-fitting o-ring or flashing on the glass-filled nylon parts.
I put Agile Offroad’s larger o-ring on my Grenadier’s PS cap as a preventative measure for angled terrain - it still doesn’t weep.
edit: What happened after the first 30 years? I replaced the PS reservoir (when I replaced the hose) with the latest Porsche / BMW part because it has a barb molded on the integral plastic low pressure return fitting, unlike the 1994 version. No weeping on the new reservoir either.
