My Mom bought the 1Z stuff... still hasnt used it! And my old BMW has a broken washer fluid pump... so yeah.
What year/model of "old BMW" do you own?
Autozone sells washer fluid pumps (TAAP Corp. brand) for most BMW's starting around $15. Or, Bavarian Autosports have them (Siemans brand) around $40. Ebay is loaded with BMW pumps. And of course BMW dealerships (much more expensive)
Replacing the washer pump on most vehicles is relatively easy...it's probably a friction fit (pull-out old one/push-in new one) or a "twist to remove" fitting, often 'hidden' on the back side of the reservoir tank.
Here's a basic procedure...Your BMW model may vary a little.
Disconnect battery ground. Then it's just a matter of removing (siphon-off) the old tank fluid; removing the tank hold-down bolt to loosen it from the body panel; removing (or lifting-up) the heat shield to expose the pump; remove the fluid level sensor; remove the pump sensor and hose; pull out the old pump; inspect/clean the tank filter. Reverse for new pump install.
Reconnect battery ground. Partially fill reservoir with distilled water to test before securing tank. Completely refill reservoir tank with your choice of washer fluid, appropriately diluted with distilled/deionized water, for your particular climate.
Just an idea....One way to have an operational windshield washer fluid system, if you should so desire. It's a safety feature that is needed on occasion, I'd venture to say.
Bob