Reply to "Radiators?"

Mikael, sometimes its related via whats called a 'ground loop'. After getting your 'galvanic battery' evaluated with the VOM, try turning on the ignition and then the headlights with the meter still connected; a change in voltage on the meter indicates a bad ground somewhere, which you can generally isolate by pulling fuses one at a time. This is a separate problem that often shows up as a change in "oil pressure" or "engine temp" when the headlights are switched on. But as I said, it only works with a really good VOM; I use a $350 Fluke meter borrowed from my work. Another way you can sometimes rate your coolant's acidity is with swimming-pool pH paper; it should be above 7.0 for best longevity of light-alloys. But some anti-freezes are dye-colored and mask the change of color on the paper.