I know that this has been asked but not sure what to do.

Manual says to use 87 and dealer told me to use 91 (TX has different octane, we have 86) Have not put gas since I bought it. Not sure which one to use. I’ve read people exhaust turning red when using low octane. Is there a way to know which gas the tank has?! I am being paranoid?! Which should I use?!

Thanks all

Utah RZR Rentals