Only people that have orange blood in their veins would continue using OEM oil, filters, grease, etc. after a purchase. Any aftermarket product that meets specifications cannot/will not void a manufacturers warranty. Why? Because of the Magnuson-Moss warranty act that prevents this deceitful practice. Does Kubota have a refinery somewhere? Caterpillar does this too, and they've been called out for it many times, and they lose every court case over it. In fact I'll bet Kubota has too.
This article explains what the Magnuson-Moss Warranty Act is and how it affects consumers.
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