If you plan to keep the car, switch it to NPG. I just did my standby generator, and it seems to work fine. It can also be run at zero pressure and boils at 370*, so no more worries about overheating. It also eliminates problems with electrolysis, corrosion, and cavitation. It's a little pricey, but you only have to do it once. I'll probably do my signature car when the next AF change is due.
www.evanscooling.com.