I use shell 91 for any vehicle that has high performance aspirations, or might be sitting for longer periods. The reason is that is does not contain ethanol, which can gum things up, and can eat rubber parts, esp on older cars.
Petro Canada has ultra 94, which contains ethanol, so I don’t touch the stuff.
Any modern car can compensate for fuels of lower octane rating.
I once experimented on my XC70. With the cheapest Shell it would do 0-100 in 9.5. With 91, 7.5 seconds. In normal driving, I couldn’t tell the difference.
This reply was modified 5 months, 2 weeks ago by ottom.
Excellent. Really appreciate the feedback and will be happy to stick with Shell. Also have a G37, only use Shell 91 and it has performed very well. Your Volvo experiment sounds fun, might give it a go. In the G of course. Cheers
You’ve received very good advice. My car is tuned (turbocharged) for 94 octane. Rather than use Ultra 94 with ethanol I use Shell 91 (real gas) with NOS Octane Booster to bring it up the extra 3 octane numbers.
The results are very strong, no knock and no moisture contamination in the blow by. It’s a win win for any high compression motor.