I was considering switching to Rotella T6 5w-30 on all my diesel equipment (2 RTV1100s, Kubota M126, 2001 ford 7.3) but i saw a thread on nettractortalk that stated the manual for Kubota says not to use CJ-4 rated oil in non DPF engines. In the Lubricants, Fuel, and Coolant section, it just states CF or better. In the notes section after that it specify CF, CF-4, CG-4 or CI-4 for everything except external EGRs, and CF or CI-4 for external EGRs. I dont quite know what constitutes an external EGR. However, T4 and T6 both include Cl-4 in their specs. Is that all that matters or do I need to find oils that don't include CJ-4? I am probably overthinking this, considering I have ran T4 15w-40 in my 2012 Rtv for about 8 years with no problem, and T6 has the exact same API ratings, that I can tell. Sorry if this has been discussed other places. I looked around the site and didn't see anything quite the same, but I could have missed it.