Z4-forum.com

They are having similar conversations over on 3/4 Series UK Bimmer Forums.

The general thinking is mixing of different manufacturers/types of washer fluid.

Goes along the lines of use BMW fluid only, though many aren't prepared to pay for the significantly higher priced BMW product, unless bought in seriously larger quantities.

Link provided here: http://f30.bimmerpost.com/forums/showth ... ?t=1196561

Mods. If linking not the done thing on here, I will remove it.

I use only BMW approved stuff and still seen a large build up of crud, BMW tried to charge me for it and I showed them receipts for all the official screen wash I'd ordered from them and they covered the 'repair' under warranty

willgill wrote:I use only BMW approved stuff and still seen a large build up of crud, BMW tried to charge me for it and I showed them receipts for all the official screen wash I'd ordered from them and they covered the 'repair' under warranty

So it looks like whatever you use it will get gummed up eventually!

I put Tesco's finest in my E46 2 years ago and the washers are still working fine. I just won't put anything else in it and it should be fine for another year or more!

To be honest it is such an easy job it's no big deal if I do need to do it every 3 or 4 years.