[DodgeMan1]

Just curious if anyone has ran 87 over 89 in the tank?

 

[jkelly16]

Have never done that. The 6 speeds w/5.7 require 91 octane, the auto's recommend 89 but says 87 is ok. Never wanted to take the chance of getting a bunch of spark knock from the low octane.

 

[MIDNITE RT]

Car has run very well over the last 5 + years using the recommended 89 octane.

 

[MOPARMOM]

I have a 5.7 Auto.....never given her anything but 91+.

 

[DodgeMan1]

This is a 5.7 auto and after using premium gas for 10 years, going to mid grade was a nice switch. I have to say with the v8 and wanting to save a few bucks and the manual mentioning it I am just curious what's the worst that would happen if I started to run 87...?

 

[MommaBetty]

I know one member who runs 87 octane and he says it is no problem whatsoever. I am using 91 in mine, just don't want to take any chances.

 

[BAD GRANDPA]

Have used 89 octane since day one. Good performance & mileage.-

 

[jkelly16]

Based on your other post about driving with the pedal to the metal, I would not use 87. I'm no expert but there's a couple of different spark knock types stored in the pcm. Short term and long term. A little bit of short term is not a big issue but if you constantly get long term it will pull timing and using the lower octane increases that chance. Of course using too high an octane is a waste of money to. Maybe someone that knows a little more about this will chime in.

 

[TikiMan]

I only feed it Chevron 93 octane from day 1. I also only run 93 or 91 in all my motorcycles.

 

[cdahl383]

The 5.7L requires 89 octane w/ auto trans and 91 octane w/ manual trans per the owner's manual.

You can run 87 octane in your car but the computer will pull timing to compensate for the inevitable spark knock that will result from using a poor grade fuel in a performance car.

I personally do not understand the reasoning behind using 87 octane over 89 octane just to save a few bucks when these cars cost around $30K+ brand new.

It's generally a 10-20 cent difference between 87 and 89. If you drove 12,000 miles per year averaging 18mpg between city and highway you would burn around 665 gallons of fuel. With a 20 cent price difference that equates to about $135 per year in savings, or $11 per month. I would think that there would be easier ways to save $11 per month if the budget is tight and feed the car the appropriate level of octane so it's happy and running properly.

 

[HemiMetal]

I usually run 89 (always top tier), but over the past 2 months I've been using 91 since the price was so low. Can't say that I've noticed any performance advantage, and because Dodge says that no benefit is derived from using octanes higher than 89 in a 5.7/Auto, I'll probably switch back to 89 now that gas prices are on the rise again.

 

[boyohboy]

I use 87 in mine and switch up to 89 when I travel on those longer journeys out of town. I have yet to have any problems what-so-ever. I do visit only reputable stations in town and try to find only trusted names on the road when traveling. I used to use 91 at times but having the auto and not running a tune I figured I was just wasting gas and money. I don't think I am the best candidate to refer to when it comes to gas usage because I only rolled a little over 10k this past summer. But the Challenger does run over 10:1 compression and does do better than my 69 Camaro did with Regular pump gas, I had to run 91 or better with that. I also run the 89 when higher temps are forecast or if I expect to do spirited driving to further reduce the chance of knock. Great Car! I truly believe this car to be an engineering feat like no other and runs the way it was designed to do! Enjoy the Journey! Lou.

 

[DodgeMan1]

Thanks folks.
Yeah I've been wanting to try it because the manual says you can....

 

[cdahl383]

I would think in a pinch it'd be fine but on a regular basis 89 octane does not cost that much more and is what the engine was designed and tuned to run on.

 

[Sosa]

I actually averaged 16.5 mpg mostly highway on 87 over a full tank . Switched it to 93, got 21.5 with the same basic driving conditions. Also, the performance increase from switching to higher grade fuel is night and day.

 

[redline14]

I run 87 in mine and never any problem or knocks (5 speed automatic), I did try 89 a couple of tanks and it's funny but true, I noticed no improvement of performance but I lost MPG.

From the owner's manual.

The 3.6L and 5.7L engine (with automatic transmission) is designed to meet all emissions
regulations and provide satisfactory fuel economy and performance when using high-quality unleaded gasoline having an octane range of 87 to 89. The manufacturer recommends the use of 89 octane for optimum performance.

The use of premium gasoline is not recommended, as it will not provide any benefit over regular gasoline in these engines.

 

[Desertguy9355]

I ran 87 when I first bought my Challenger, mostly because I didn't bother reading the manual and the guy at the dealer said that 87 was fine. Ran it for a couple of months. However, I was noticing that it just didn't sound or feel right. I was looking in the book, saw the 91+ reference for manuals and have been going with 91 ever sense. :smileup:

 

[redline14]

I will say though if I drove mine in the winter I probably would go with the 89 just because the winter blend of gas is crappy here in IL, I figure if it hurts your mileage it must be a lower octane and or quality.

 

[p940]

i ran 87 in my 2010 r/t on trips that i could burn the whole tank. around town i put 93 in and could notice the differance. i put 55000 on that car, plugs were clean and burnt even.

 

[the greek mopar man]

93 octane here , its required with the supercharger. my sons challenger will be using 89 octane