I have a 2004 Silverado and tried to find out the capacity of the windshield washer reservoir by looking in the capacities section of the owner's manual. Of course, this capacity information is not in the manual, so yesterday I called Chevrolet and the representative said that he didn't have the exact capacity for my specific truck, but that the capacity of the windshield washer reservoir was "about 1 gallon." Because of the bizarre shape of the washer reservoir, it is impossible to estimate its size. I thought about draining the fluid so that I could measure the amount that I put back in, but there doesn't seem to be an easy way to drain the thing.
The representative was unable to tell me if the factory-installed windshield washer solution had antifreeze protection, but he guessed that the solution was probably GM Opticlean, part #1051515. I still don't know if the GM product has any antifreeze protection. During the time that I have owned the truck, I have put in about 1 quart of washer fluid (which has enough methanol to protect from freezing down to 20º F) into the reservoir and the reservoir appears to be about 1 quart low now.
As usual, the owner's manual offers little help in selecting the proper antifreeze solution for the windshield washer solution:
"If you will be operating your vehicle in an area where the temperature may fall below freezing, use a fluid that has sufficient protection against freezing." I'm hoping that Mac's Concentrated Washer & Solvent will fulfill this requirement. And now that I know that the capacity of the washer reservoir is "about 1 gallon", I can better guess the proper solvent ratio to protect the fluid down to 0º F.
Has anyone got a recipe for a non-freezing, windshield washer solution? That is, a solution that won't harm glass, plastic, rubber or metal?