My 1996 VStrom would not run well on 91 octane. It would tolerate it on a trip, but not when commuting, so the aim here was to see if there was a difference between fuel brands. I found only minor differences with Shell being best, Caltex, Challenge and BP equal, and Mobil slightly behind. BP 98 was slightly better than than all others, but not by enough to warrant the extra cost. This test was carried out over two years and aproximately 40,000 km.
My second VStrom gave very suprising results. First of all it felt as if it ran better on 91 than 95 or higher, and it wasn't long before the results confirmed it. The Mobil test is not significant as Mobil is the only fuel I don't have a fuel card for, so I use this brand only when there is no alternative. This test is over 2.5 years and 45,000 km.
BP 91 - 16.6 km/l __________ BP 98 - 16.0 km/l
Caltex 91 - 16.5 km/l _______ Caltex 95 - 16.5 km/l
Challenge 91 - 15.8 km/l ____ Challenge 95 - 15.3 km/l
Mobil 91 - 15.1 km/l _______ Mobil 95 - 16.8 km/l
Shell 91 - 17.2 km/l ________ Shell 95 - 15.9 Km/l
Overall 91 - 16.5 km/l ______ Overall 95 (or higher) 16.2 km/l
Bookmarks