mmmm....nothing quite like the sweet smell of poison in the cabin!!
I've been using contaminated methanol to make screen wash for a couple of years now and so far haven't gone blind.
I did try to find the optimum %age when I started using it but couldn't and just did a bit of experimenting. It works really well ... glob of methanol, a glob of cheapest washing up liquid you can find (must be cheap as I think more expensive brands may contain lanolin or similar which smears on the screen), and top up with water.
You can indeed smell it in the car if you wash for a long period, but I don't think the odd waft of fumes will do any harm and, under several layers of dirt, surrounding paint work seems is unblemished.
Thinking about methanol as anti freeze when neisel started this thread, I stumbled upon a company in Colorado USA who make methanol based screen wash. This page (
http://www.clearchoiceantifreeze.com/products.html ) states their screen wash is 30% methanol as follows ...
Clear Choice Windshield Washer Fluid
As a service to our antifreeze customers, we proudly offer you windshield washer solvent. Our washer fluid is the finest in the business. We blend our windshield washer fluid using 30% methanol to deliver optimal freeze point protection, while giving you the peace of mind of a 100 degree flash point. Since we deliver in bulk, you'll only pay for what you need. You won't find a better product on the market. (Available only in select areas--call for details.)
Here's a link to the MSDS ...
http://www.clearchoiceantifreeze.com/pdf/MSDS-WWFluid.pdf