Never heard or read or seen anything about those oil recommendations.

Think about this... it's not winter. You could run straight 30 weight if you wanted to.

Yeah, it'll be a little thicker than 5W-30 if it were running it in the winter, but given we're not seeing snow on the ground, it's not a concern.

Kinda like my brother's Honda, I use 5W-30 during the winter, but 10W-30 during the other three seasons. What this does is reduce the amount of oil that gets burned on startup due to the valve seal design on the car during the warmer months where 5W isn't really necessary.

Any of this make any sense? It does to me. If it didn't work, I would've rebuilt several engines already.

Our Suburban with the 5.7 called for 5W-30, but we've always ran 10W-30 in it. 214,000 miles and still going strong. 20 psi at idle when warm, 40 or more when you get on the throttle. 60+ when idling cold. What I find strange is that many people that are selling their Suburbans of the same vintage (1993-1999) stated they had the engine rebuilt or replaced. Why? It shouldn't be giving you a single problem. Ours leaks a tiny bit, but still doesn't burn any oil. Conspiracy? Maybe...

Also, my Ranger's oil fill cap says nothing on it. General mechanic's rule is 10W-30 goes in when that's the case.

However, my dad's 2005 Taurus has 5W-20 printed onto it. (I believe it's a Vulcan as well) So that's what I use in that. I noticed that it burns some oil... (160,000 miles on it) I bet it's because it's so thin that it gets through the valve seals that by now, are starting to wear out. About a quart every 4000.

My 1984 Maxima with the straight six has 178,000 on it and doesn't burn a single drop of oil, even with 4500 miles on this current filter and oil. I gotta change the oil, or at least the filter on that soon.

 

That's what I used to do in my old '97... 5W30 in the winter and 10W30 in the summer.

 

How many miles did you put on that 97? What engine?