2009-2015 Cadillac CTS-V General Discussion Discussion, octane in Cadillac CTS-V Series Forum - 2009-2015; Need opinions on octane recommendation . In ontario we have 91 V-Power shell (no ethanol) and 94 Sunoco (10% ethanol). ...
Do you have any modifications tha tmight make you believe you need more than the 91 ocyane the owners' manual recommends?
HIgher octane ratings will do nothing for you (except lighten your wallet) if the lower octane rating doesn't cause premature detonation.
Another thing to keep in mind is that ethanol has a lower BTU content than gasoline (i.e. less power), so your computer compensates by dumping more fuel into the cylinder resulting in increased consumption on top of the premium you paid for the gasoline.
IF you have software or some other way to determine how much knock you're getting you can compare the 91 vs. 94 octane, or compare your performance at the track with the two fuels. If the 94 provides you with some benefit go for it, otherwise save yourself the cash and stick with the 91.
Some good points here Looney100 , the manual suggests 91 or higher , and for best performance the manual suggests 93 octane . I've not used any gasoline with ethanol in it , period . I've only used shell 91 V-power at this point . However , I imagine that some people on this board have compared the two gasolines here so I would like to get their opinions .