I'd run Mobil 1 0w30 and sleep well... It will be interesting to hear what you think about the 2.5 at our altitude once you swap the gears out. My experience has not been great especially with the Auto..
After seeing plenty of worn out 2.5's.... can blame the oil on some and maybe the drivers on others, I'd recommend the higher HTHS and/or higher zddp oils. I am willing to sacrifice a couple mousepower to the thicker oil. Any oil with an HTHS >3.5!
Any 0w40 or 5w40 from /Mobil1Castrol/Valvoline/Pennzoil... availability!
Rotella T6 5w30 or 0w40
Delvac Extreme 10w30
And yes, that Euro Pennzoil L pictured would be a good choice too, as would the euro choices Valvoline/Mobil1/Castrol/Fram/Supertech or other competitors!
I'll recommend the purolator boss, wix xp, and napa platinum oil filters. Size is for you to choose(go biggest that'll fit).... ph16, ph43, or ph8a equivalents.
Get some fresh any brand synthetic ATF+4 and new OE filter in the transmission, and some ATF+4 or synthetic ATF in the transfer case(231?). And, dump the front/rear diffs for some good locally available synthetic gear oil. PSF? check to see if its ATF4 or domestic PSF.
Owners manual can be found on ebay or your local salvage yard. Might even find it on amazon(used book).
That’s a tough little engine, although as others have said, it’s slow,….very slow.