talcaraz

When I purchased my 2008 Jeep Rubicon JKU, I asked the same question. I went to the owners manual, which read to use 87 only. It also stated that using premium gasoline would not provide a benefit over high quality regular gasoline, and in some cases may result in poorer preformance.

As a result, I have used only 87 (even in the summer time in the Mojave desert) without any problems.

Hope this helps.

Chrislh

I won't put shell gas in my Jk anymore. I lost 1.5 mpgs from the chevron gas I normally use.

drumnatural

I'll use 89 just for the slight bump in octane to help avoid pre-detonation.

12thman

You might want to read my post from yesterday.

Chrislh

Interesting. Guess the additive makes a difference.

Good info!

Biscuit

Not true. (1) All gasolines, regardless of brand, are required to include a minimum additive package to keep fuel systems clean and comply with federal and state emissions requirements. That is a regulatory mandate. (2) All gasolines, regardless of brand, buy their additives from a single source in Houston, TX. (3) Some additive packages are brand-proprietary (like Shell or Chevron-Texaco), but it's all marketing hype. Any differences from brand to brand are neglible. (4) All suppliers - and hence retail vendors - share the same gasoline pipelines and distribution terminals. You're buying the same gas at the local Stop & Rob as you are at the big name marquees.

12thman

A lot of factors can change MPGs. Weight, temp, speed, terrain, wind, etc. I think you would need to run several tanks of each to get a good idea if a particular fuel or octane works better or not. I work with two guys that have F-150s with the eco-boost engine that swear a 3 MPG increase with 89 octane even though the owners manual calls for 87 minimum.