[pparks1]

In my wife's 2015 Durango, it's a lease. So, we will just change the oil when the EVIC tells us to and will use whatever the dealer puts in it.

In my 2013 Passat TDI, which I am buying, it uses a Castrol full synthetic blend. VW covers the maintenance for the first 30k miles, and they do oil changes at 10k, 20k, and 30k. So that is what I have been doing. Those who have sprung for Blackstone used oil analysis tests show that the oil is just fine at 10k. My plan is to do my oil changes about every 15k. That comes out to about once every 9 months or so with the number of miles I drive.

 

[pparks1]

TDI requires 0w-40 diesel oil. I did not know Castrol semi syn is spec'd for diesel.
On the topic, most synthetic oil are petroleum anyway. A conventional labeled motor oil should be fine for 6k miles. I would not leave any oil in my sump for 10k miles.

Actually the new Clean Diesels with the DPF system, use a 5W-30 blend, which used to be called Castrol SLX LL03 and it's now been re-labeled as Castrol Edge Professional LL03. It is specifically a low-ash oil confirming to the VW 507.00 requirements on these new TDI engines. It's been engineered between VW and Castrol for the VW and Audi engines. It's a full synthetic and is designed for long drain intervals.