I think there is a LOT of gray area with regards to the term "synthetic" and I do not really care to even use that as a determining factor for the oil I use.
I use, and have always used, oils that meet both the prefered weight and the specific VAG spec that is called for. Synthetic, semi-synthetic, Group 3, Group 4, does not contain dolphins, does contain dolphins, may contain peanuts, I don't care.
We switched to the Pento HP2 a few years ago because it covered the widest variety of cars that we would use it on. It carries most of the VAG oil specs for cars sold here (both gas and diesel) as well as MB's newest spec, BMW, Porsche, etc. I was always a Castrol guy, and continue to run it in my '91 Jetta, my '82 Vanagon, and my Japanese vehicles. But with the newer VAG specs, Castrol really messed things up by not making the stuff widely available nor even keeping their American branch up on what is what. Doesn't help that the dealers, so often clueless about oil specs anyways, get even more confused by the Syntec/TXT/SLX/LL03/5W40/5W30/etc. nonsense that Castrol has been feeding them over the last 10+ years. No wonder they can't put the correct oil in, it keeps changing and they [Castrol] will not sell the stuff in bulk!
My own PD has (so far) been fed a steady diet of 5w40 TXT since new, and that supply has run out (I bought a bunch when the car was new, enough to get me to 100k miles). And once again, I have tried several times, as a jobber and an authorized Castrol reseller, to get it in bulk with no luck, or to get ANY 5w40 Castrol product meeting the 505.01 spec in ANY container and again met with failure. I've even called all the local retailers of Castrol's new 'Edge' line, and nobody can or will get 5w40 in.
So I too will be switching it to Pentosin in a few thousand miles, and I feel safe doing so because of so many customers' cars that have been running it without troubles for so long. And the only reason I did not switch sooner was because, as I said, I bought enough TXT when the car was new to get me for a while.
As far as a median Pento HP2 mileage, that would be tough to say. Lots of VEs with 250k+, especially some of the older ones. Much of the PD fleet has been hitting 100k lately (I know this because I have been doing just as many if not more PD timing belts than VEs, and that is not including the BHW engines due to the BS upgrades).
Also a boatload of gas VAG cars, Sprinters, etc. that we run it in. And every one of them with the exception of some sludge-prone 1.8t cars are running 10k mile intervals.
