Hmm... One wonders about "standardization." I'm running 5-30 Castrol SynTech - oops, now they call it "Edge" for some reason - in the Corolla and the Crown Vic. The Jeep has the same oil in 10-30. The Corolla (about 168K last time I checked) and the ex-cop Crown Vic (just past 190K) are our "commuters" right now. The Grand Cherokee gets cranked up if winter really gets bad, but since it got the 5½" lifted suspension and 33" tires, it gets lousy gas mileage. It's pretty much for going up into the hills or pulling the trailer.
My '96 Suburban has been sitting for 2-3 years, with a bad transfer case. But its 454 has 261,000 miles, has never had the heads off and never needed a quart between 3,000 mile changes. I ran Castrol 10-30 for the first 150-200K, then 20-50 except in winter (10-30 again) and added some HyPerLube.
If I remember correctly, I have Delo 400 15-40 in my seldom used '86 F250 (seldom used because unless you're rich you need a good reason to start up a carbureted 460 these days).
I haven't run my 1966 International for at least two years. I think I had the 20-50 Castrol in that. Eventually, I hope to get that and the Suburban back on the road.
I'm thinking life would be simpler if I standardized on one oil, and stocked up on that.
Oh yeah, my Suzuki DL650 is using Shell Rotella 15-40.