Back in 2000 when I bought a new 7.3 diesel, it takes 15 quarts of Rotella 15-40.
So I bought a 55 gallon drum of it.(On the second drum now) Sam's club has them. It is really handy living rural and not have to go to town to get oil.
Extra filters also.
I use it in everything except the two newer rides that require synthetic.
Mobile one is what I use in those.

And get this, The 2018 Tacoma oil change is every 10,000 miles.
Just did the 3rd change and the oil coming out still looked clean and not black.

Don

1967 GMC 9500 Fire Ladder Truck
"The Flag Pole"
In the Stovebolt Gallery
1946 2-Ton grain truck
1946 3/4-ton pickup,
1953 1-ton pickup
1957 1-ton flatbed dually,
1954 Pontiac Straight Eight
Of all the things I've lost in my life, I miss my mind the most!