Did a fair bit if research on BTOG. Seem diesel seems to coping with contaminants on their oil analysis. But again the consensus is the more you drive the car the less it contaminates. Same as what guys have been saying here. Diesel is generally cheaper too...$50-80 for 10 litres.
HPR diesel is a very good oil. Spoke to a guy at autobarn a while back that used to work for them and do a lot of r&d, was in their for ages chatting about oil. He made some really interesting points about oil in general. One that really made sense was that if you change your oil every 3 to 5 thousand km then full synthetic is a waste of time and that they are really designed for extended oil changes. On all the testing they did with all the oils and brands, diesel oil stood out in most areas of the testing. Interesting. But again for oil changes longer than 5000km on high performance cars synthetic is where it is.
on E85 oil has to be changed more frequent so the advantages of full synthetic is irrelevant and that's where diesel oils come into their own with the high zinc and cleaning properties. Anyway thought I would share.