Oily fluid in windshield washer resevoir

I turned on the windshield washers in my husband’s 95 volvo wagon and the windshield became smudged and totally impossible to see through. I pulled over to see what was in the resevoir and found an oily substance. It looked a bit like congealed olive oil. I emptied the resevoir by running it until it no longer sprayed. Needless to say, I had the oily substance all over the windshield and front end of the car. After 3 hours of cleaning the car off and rinsing the resevoir with dawn mixed with water, I think I’ve cleared the system. My question is… what could this fluid be? My husband says that he has not put anything in the wiper fluid resevoir. The only other person would be the mechanic. I plan to ask him, but thought I’d ask you first.

Do you folks frequent quick lube-type places? Or have you used one recently? Lots of careless things go on at places like that and you could just feel lucky that your problem was minor. Others lose their engines when the oil gets left out or the drain plug doesn’t get tightened…

It just sounds like something other than washer fluid got added.

No. We go to a Volvo specific mechanic who we’ve found to be very honest and reliable. Have not gone to a Jiffy Lube type place in years.

A windshield washer fluid reservoir and pump is a unit totally on its own.

There is no way any oily substance can enter unless dumped in on purpose or by mistake.

I suspect your problem was caused by Mistake. (Likely an honest one)

Most cars have two similar plastic reservoirs. One for washer fluid and one for engine coolant. A 50-50 mix of glycol and water with a little alcohol added will make quite a mess when sprayed on the windshield…

Sounds like it could be that coolant was put in the wiper fluid resevoir by mistake. Hopefully, it won’t cause long-term problems with the washer fluid pump. Do you think that using the dawn mixed with water was ok to use to flush the gunk out?