I went through this situation years ago with buying brand name oils and machinery company oils. I did an indepth study, got all the company specks on the oils and made the decision to go with Case IH oil!!! Yes it is true all oils whether it is TEXACO, ESSO, JOHN DEERE, NEW HOllAND, are all derived from the same base stock oils, oil is oil. But the oils you buy to put in your tractor are not the same. Different companies take these base stock oils and add different additives to make a particuliar oil just for the application it is to be used for. Additives for oxidation, friction, detergents, the list goes on and on are added in different degrees to make up the oils. The more additives you add to the oil the more the costs go up. All the major companies handle fleet oils that they sell for the trucking industries that they say are suitable for agricultural purposes and are reasonably priced. If you are a penny pincher then go with the ESSO, TEXACO, SHEll brands, they will work, but if you really care about your engines and want the very best protection for them, go with the manufacturers oil. THE FACTS--- trucking fleet oils are made for the trucking industry specifications. Trucks running 60 mph, 1300 rpm for hrs on end with a clean air supply, whereas a farm tractor pulling at 2100 rpm under extreme load where it is lugged down 500rpm at a time and is running in a cloud of dust aren't the same conditions by any means. If one checks with his oil supplier he will find he also can sell you an EXTREME SERVICE oil, but it will cost more money. Farming and construction are considered extreme service conditions and engines working in these conditions should be using oils capable of the task. These truck fleet oils will do the job, but manufacturers specked oils will do a much better job under agricultural and construction conditions. If one has to stretch an oil interval change a few more hours over the recommended period it is better to have the manufactures' specked oil in there. I use Case IH 15w 40 oil in every thing on my farm including my wife's explorer. I buy it in bulk from my dealer, he fills my drums over and over.