I see you guys quoting info here a lot about using a "10-40" oil. That viscosity has been obsolete since back in the 80's as I recall, and I honestly know of no blender putting out a 10-40 in Diesel Service oil. I know of no CJ-4's or CI-4's in 10-40 available by anyone. (now--someone prove me wrong!!:laughing

I have a 72 inch Kubota mower, the 31 HP model I think it's a Z331 or 336, the biggest dude they make. I just gave it the first oil change. I put in Chevron Delo 400 10W/30, CJ-4. That baby mowed 5 hours the other day at 3/4 throttle, it was 90 degrees, real heavy grass, and it purred like a tomcat, burning 4.3 gallons of fuel. Don't be afraid of 10W/30 in a premium oil, or the 5W/40 synthetic either, year round. Delvac, Rotella, Delo or even Conoco or other such products---they work and are excellent.. No need to fret.