I’ve been using 95/98 since I own my Aurion never used 91 and I’m thinking of using 91 these days.
Now I think I’m gonna just stick with 95:)
I bought my aurion three months ago and now I’ve done 8,000 km with it. I usually get around 7.6 l/100km on highway with 95RON and Nulon 5w30 full synthetic oil (Non PAO based oil (doesn’t matter much here)). When cruising, no acceleration, and at 100 kph, I usually get around 6.9 l/100km. By the way, back in my home country, China, the OE engine oil for 2gr-fe engine in a much heavier vehicle, highlander, is 0w20. With 0w-20, the Petrol consumption could definitely go lower.
98 doesn’t provide obvious extra gain than 95 to me. I used it only when I couldn’t find 95 at the gas stations.