Interesting question since I presume you;re referring to Windshield washer fluid as Methanol? Water in the washer fluid turns into steam and methanol burns pretty clean so your engine should run cleaner. If you get the residue from the windshield washer fluid I'd buy a different brand as the residue may be the soap or whatever else is in your washer fluid. It amy also be a bad jug you got?
Difficult to guess without more info. My pipes also have some brown on them, but I drive a lot and seldom use the water/**** so my brown is from driving without it and considered normal. I also have soem deposits on my Stealth tailpipes - TT, no w/m inj. Your deposits may just be using more fuel because you're making more power with the blower, mixture, etc.
Ted
Ted
