Well, my 98 is a 3.0. And I've said it many times, been running 20W-50 in it for 19 years, winter or not. Never had any trouble, and boy does 20W-50 quiet down a noisy engine. LOL.. I run good old Castrol GTX petroleum oil.
And I agree with what was said above. Long ago, the heavier oils were normal. Harley guys used to come into the store and buy cases of Valvoline 60 weight. Castrol GTX 20W-50 was our number one seller. Then auto makers ahd to start meeting CAFE requirements. And yes, thinner oil helps with this.
I used to be able to take my Ranger to the valvoline place and they would put in twhat I told them to put in. Now days, every damn oil place out there wants to fucking argue with you, and refuse to put in anything but colored water 5w-20. So, I do my own now, and put in what I want. I run 20W-50 in just about everything I own. My 98 Ranger, my 06 Suzuki M1800R, my 08 Suzuki B-King.
Currently running 10W-30 in my Lightning. Oil cap says 5W-20, but the 10W-30 doesn't appear to hurt a thing. Some guys I know with Lightnings run 10W-40 in them with no problems. I had a 99 Lightning back then, and the oil cap said 10W-30. My 04 says 5W-20. Same engine, not a thing different.
THe oild oi cap that was in my Ranger said 10W-30. If you can run that, 10W-40 and 20W-50 aren't going to hurt anything. The hsop manual I have for my Ranger even talks about 10W-40 and 20W-50 in the oil usage graph. The oil change shop down the street from me says the 98 Ranger is a 5W-20 vehicle. I told him BS, and showed him the shop manual. He even wanted to argue with me after that. ASSHAT.