I was just in the same boat as you, doing my first maintenance on my new Kubota. I live in a rural area around a lot of farmers and big tractor owners, So I asked around, and I done a lot of online reading and reasearch. I wanted to also use the absolute best product - price was of no concern, only quality. What I found is that by far the highest and most numerous recommendations were for Shell Rotella T6 Fully Synthetic. Being in Florida, I went with 15W-40. Just look at the bottle good, make sure it is for Diesel engines whatever you buy. Gas engine oil and diesel engine oil are different. Also note that if you go for the shell rotella T6, make sure you dont confuse it with the Rotella T5, which is a slightly cheaper option (still very good oil) but is a synthetic blended oil. T6 is the high dollar, fully synthetic option. Its about $20 - $25 per gallon.
+1.... I get mine in 55 gallon drums, quantity is always cheaper. I use it in everything, cars included.
I run Rotella T6 in just about everything I own, including my 09 Goldwing. Quieter? Absolutely... gears don't slam together after 200 miles of riding. Kubota cranks just fine when it's 10 degrees outside.
+1. I am not sure about Rotella, but Amsoil publishes performance tests and white papers on their website. I also personally run series 3000 5W30 in my diesel with a dual bypass filter setup. I change the filters and send a sample in for analysis yearly. End result is that I have not had to change my oil in over 15 years. There are really only two things that can happen to oil It can either get dirty or break down or both. The dual bypass keeps it clean and as long as the oil doesn't breakdown, no need to change it.
Any SH or SG rated "motorcycle" or "marine" oil is going to be easy to find and be loaded with anti wear additives and detergent compared to new rotella.
