Ok, I have been retired from esso for 2 yrs last may.(thankyou god) I just called the lab and we don't manufacture the xd3 oil in Canada anymore apparently. It is now all in the USA and is called Delvac. (my "supply" of xd3 hasn't ran out quite yet LOL) Rotella T is Shell's equivalent. They are made with conventional,crude derived, base oil which is indeed inferior to synthetic base oils but that is not an issue if you change the dang stuff. Under extreme extreme heat and pressure the base oil lube molecules will get thermally cracked into shorter chain molecules that will degrade their lubricating qualities.I completely checked all my oil ,in and out , on every oil change and worked my way up to 60hr intervals. The oil always met new manufacturing specs every time in terms of viscosity and additive levels. In other words could actually go longer but I chose to stay around 60 hrs.