I have a 95 GMC c2500 3/4 ton Vandura, with a 5.7L V8 that I just bought.
I changed the oil and filters, and tried to do a radiator flush and fill, but I can't get the drain valve to open. Am I turning the right piece? It's the little white plastic one near the bottom on the driver side.
I've never had an issue opening these before, and was just wondering what I should do to avoid breaking it.