The difference is that the automatics are tuned to run on 89, but will run on 87,the 6-speeds are tuned to run on 91...Diablo Sports said the 6-speeds have 2 degrees more advance. But are saddled with torque management that pulls timing with every shift. In 2010 automatic was standard and 6-speeds were an extra cost option.Since 2011 6-speeds are standard and automatics are an extra cost option.
Probably not unless you're having detonation issues to the point of pulling timing which isn't likely unless you're getting really crappy gas.
Im getting KR even on 93 here in Texas. Some stations are worse than others but even the best gas I can find is still robbing a little power. Is running 89 hurting your performance? From the logs and tests I have ran yes it is, but not enough that you would notice a huge difference by using 91 unless you are getting huge amounts of KR.
I kind of slip thru the back door somewhat. At the half mark on the gauge I go for a fill up. Every other fill up I bounce from 93 once to 89 at the next fill & I have the (quote,at least to me)peace of mind that I am hovering at the manuals suggestion of 91. My salesman said 89 is o.k. for my 2014 r/t , but I'm not buying it. Always use TOP TIER FUEL. I think the site is (toptiergas.org) for a listing of government accepted manufacturers. I stick with Shell. It's easy to find almost anywhere.
Are you sure your owner's manual specifies 91 octane? I thought that 89 octane was recommended for the 5.7 engine. If I am right, using 91 or 93 octane will do nothing for you except waste money. My 6.1, however, requires 91 octane. Otherwise, the PCM will retard the timing (to prevent pinging) and my engine will lose power.
Hello Tom Thank you for your reply on the octane 91. I double checked my 2014 Challenger user guide to make sure & on P 111 at the very last entry for non-SRT fluids & capacities it shows fuel selection 5.7 engine 91 octane recommended. The same p 111 starts the SRT fluids & capacities & it shows the 6.4 as requiring 91 but it does insert (or higher) I've been on the Forum for only about 2 wks. or so but I enjoy reading your threads. You are very knowledgeable on our cars. Can you point me to either a Sticky or somewhere that I could download a copy of the possible DTC codes that could happen with my 2014 R/T for my future reference. Thks again. Rena
The manual for my '11 R/T Classic calls for 89 octane and that's what I've used over the past two years that I've owned the car. Until about a month ago when I grabbed the 93 octane hose by mistake at my nearby Shell station. My "butt dyno" says that the car is more responsive and a little peppier on the good stuff.
I always use what the manual recommends unless there is a "tune" being used. Some of the guys around here have had issues with knock sensors when they use a different grade than what the car is tuned for.
