Re: Cold weather starting issues
I doubt that it is the oil. I have ran Valvoline 15/40 since my truck was new in temperatures from -40 to +110 and the only time that I have had a problem starting it was when the factory relay went south.
You need to test the relay and make sure that it is working right. With a digital volt ohm meter test both large post with the key on and the relay activated. You should see less than 0.3 volts difference between the two.
96 F250 XLT 4x4, 4:10 gears, 5 speed, Tymar intake and HX hose, downpipe, pyro and boost guages, coolant filter, Luc clutch