Thank you everyone for your info the Hot Rod did great and I used Premium and will probably continue did exactely as i wanted more power and more fun :0) Carman

 

 

I read & re read this thread & my owners manual. Our 09 2.4L calls for Regular, 87 octane unleaded fuel. The manual say nothing about Premium fuel with regard to the 2.4L engine.
IT DOES call for 91 octane, or higher for 2.0L & 2.2L engines. It further states that these engines will run, with reduced acceleration on 87 octane fuel.
I am puzzled, to say the least.

 

You can verify this in the search box. The '09 Manual is mis-printed. & Hi-Test IS recommended, not required. But the 2.4 is tuned to be optimal with Hi-Test.

 

4th year owner here: I run prem. exclusively now , the engine does not sound / feel as smooth/punchy as it does with premium, and I also notice better economy on prem. (probably because I dont have to put my foot down as much) If I run tank of regular it will take maybe 1/4 tank of fresh prem. before it figures out that the better gas is in there. I'm assuming less knock count allowing more timing to be dialed in

 

I run Sunoco 93 octane in my '07 2.4 for those very reasons.... makes a huge difference in mine

 

I use premium... I like it because of the extra cleaners and additives they put in it. I get Shell if I can.

 

Chevron (here) sells 100% real gas, so I use their 93 octane & get best giddyup, mpg & smooth running..

 

My '06 specifically says the 2.2 runs on 87 and the 2.4 should have 91+, can run on 87 at reduced performance levels and knock may be experienced. Frankly mine runs as well on regular and mpg is slightly better on regular, since regular has higher btu's it makes sense.

 

It's all about the compression ratios and spark advance. If an engine is designed to be optimized for a given octane level, then it's best to use that octane. Modern control systems have something called an octane scaler that, once engine knock is detected by the acoustic knock sensors, will scale back spark advance to somewhere in between the high and low octane spark tables in the ECM. This is why they state that it is permissable to use lower octane with reduced power. It is still better to use the correct fuel, because knock adaptive spark has to see some engine knock before it kicks in, and is always trying to restore spark to the high octane value. Not a good thing over the long haul, and can be quite destructive on a forced induction motor like the LNF 2.0.

Octane is a measure of resistance to knock. Nothing more. Cars calibrated for 97 octane do not run better on high octane. This only occurs in the minds of the owners. In fact, as mentioned above, lower octane fuel has a slightly higher btu value and will get a hair (I won't say what type of hair) better MPG than high octane on an engine calibrated for low octane. Gasoline companies sometimes reserve their fanciest detergent package for their most expensive grade of fuel, but this is completely unrelated to octane value. Yes, over the course of tens of thousands of miles, a better detergent package will keep your intake valves a little cleaner, but anyone who thinks that a single tank full of ZOMG wonder gas is going to anything other than increase BP's bottom line needs to see me about this oceanfront property in AZ I'm trying to unload.