According to the BX2380 Kubota Operator's Manual (page 73) CJ=4 engine oil "cannot be used on this tractor." Kubota engine oil has a CJ-4 rating along with others. Should Kubota engine oil not be used on the BX2380?!?!?!
I'm thinking the statement in the manual means that you shouldn't use an engine oil with
only a CJ-4 rating.
I talked with the dealership's service manager about this. I changed my oil last night and used Kubota 15w-40.
Try not to over think things. You'll live longer and be happier for it.
I find the Canola oil idea interesting. It made me wonder about using olive oil and a stick of butter.