Cooker the JD oil is great,the only thing I don't like about it is the price. I go through three 55ga drums of Delo a year,when you get into the volume the bottom line changes fast. Same with the JD Hyguard fluid and JD filters,they are very good but the price just isn't right. I use Chevron THF 1000 and Wix filters. One JD has 22,000 hrs on this system,my oldest JD's hr meter portion of the tach when south ten+ years ago with 19,000 hrs,both start instantly use little oil or smoke,what more can you ask for?I also use the 15-40 Delo in all my cars in the warmer part of the year.
Since you're from Mich. I assume you're speaking of orchard tractors,not the 300+ hp field tractors,they may have different needs. I'm running 55-85 hp modified low and narrow for tree rows down to 12' wide drive centers, in some newer blocks the trees are only 2' apart,more like a vineyard than orchard. We're talking a tight fit. My widest tractor is 52" to the outside of the rears,narrowest is 46" and they're still too wide. Too expensive also since they're special,so I try to make them last and Delo has been fine in my book.