Pedro is correct. Unless the engine has been modified from stock config by using a tuner or physical component changes then using a fuel with octane higher than that spec'd by the manufacturer does nothing. And the Hemi engine is spec'd for 89. It can de-tune itself and live with 87 but using something higher than 89 will not improve anything.

Octane is a rating of the fuel's resistance to detonation (ignition from compression, as versus spark). Engines require a certain octane related to their compression ratio and timing to avoid detonation in normal cycling. As long as the fuel doesn't detonate it all works the same. There is no 'extra' energy in 92 octane versus 89. If you change components to increase compression or if you use a tuner and change timing you may need higher octane to avoid detonation.

Rob

 

Here is my owners manual says about octane ratings.

The 5.7L engine 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.

Here is what my owners manual says about octane boosters

• The use of fuel additives, which are now being sold as octane enhancers are not recommended. Most of these products contain high concentrations of methanol. Fuel system damage or vehicle performance problems resulting from the use of such fuels or additives is not the responsibility of the manufacturer.

Also most octane boosters use MMT, here is what my owners manual says about MMT.

MMT In Gasoline
MMT is a manganese containing metallic additive that is blended into some gasoline to increase octane. Gasoline blended with MMT provides no performance advantage beyond gasoline of the same octane number without MMT. Gasoline blended with MMT reduces spark plug life and reduces emissions system performance in some vehicles. The manufacturer recommends that gasoline without MMT be used in your vehicle. The MMT content of gasoline may not be indicated on the gasoline pump, therefore, you should ask your gasoline retailer whether or not his/her gasoline contains MMT. It is even more important to look for gasolines without MMT in Canada, because MMT can be used at levels higher than those allowed in the United States. MMT is prohibited in Federal and California reformulated gasoline.

 

Boosters - no good. The only thing I use in gas is Star Tron - if I cannot get ethanol free gas. I use it in EVERY OUNCE of gas I buy whether it be for vehicle, generator, outboard, yard tool, etc...

 

I only add unicorn urine to my fuel if I can't get E10. No telling what E0 might do to my engines.

 

No, that would be COW URINE and that is what the tree hugging government is forcing me to pour into my diesel truck!


I've been sold on StarTron (or similar ethanol treatments) since my days I fished bass tournaments. I was always fighting gas line/engine problems from the ethanol gas sitting in the tank - my last boat had a 44 gallon tank and sometimes I'd go two-three months between fill ups.
Seemed like all the "seasoned" guys never had that problem and I did some question asking and found out they were all treating for ethanol. Now I've always used Sta-Bil for a stabilizer but at that time they didn't have an ethanol treatment product (they do now).


I was also ALWAYS cleaning carbs, replacing primer bulbs/fuel lines in all of my equipment I keep up at the farm. Problem is, sometimes it'd be 6 months between trips up to the farm to cut grass, cut back tree limbs and general maintenance. FIRST THING I'd always have to do is spend the first day taking apart carbs and replacing the plastic/rubber pieces that rotted away. Even emptying gas and running till dry would help much. I've been treating my gas for about four to five years now and I've yet to have to touch a carb or any gas line parts.


Now do you NEED to run it in a MODERN daily driver where you are burning through a tank every week, probably not - but I'm in the habit of just adding the product to all my gas. In the bulk I buy it, it basically costs me six cents a gallon.


Now I work in the auto restoration industry - where these vehicles were not design to be able to withstand the harmful effects of ethanol. You better believe 95%+ of the people who invest in these vehicles run some brand of ethanol treatment or go WAY out of their way for non-ethanol fuel.


I know some people will weigh in about not needing these types of products or how they are "snake oil" but I don't put ANY stock in people who spout off on something having never tried it or researching it. I have first hand experience in this one working as advertised...

 

I guess I've got plenty of first had experience not using any of that stuff We've had E10 here for 25+ years and I've never had a fuel issue. I've got boats, sleds, chainsaws, mowers, and extra cars in storage for 6-8 months at a time. I've come to the conclusion that there must be a lot of stations with leaky tanks or otherwise crappy fuel.

 

Place a common primer bulb or a piece of PVC fuel line in a cup of untreated E10 and place one in a treated cup and see what's left after a month.


We've done it...


Or better yet, talk to some of the guys in Minn. fishing bass or the Walleye trail. I've fished against quit a few guys from your neck of the woods. They all have horror stories about outboard rebuilds from the effects of ethanol.

 

Huh? So you are saying that adding a couple oz of Propanol (that is 95% of what is in Stabil ethanol formula ) somehow makes it not melt something? That is the silliest thing I have ever heard.


I guess if it does something for you then use it. But my Malibu doesn't give a rats *** about running on E10, nor does anything else we own.

 

I've not had problems with the standard blend of unleaded fuel here in MN either, and I run quite a few engines. Snowmobiles, motorcycles, chainsaw, tractor, weed trimmer, generator, pressure washer, tiller, etc. I use Sta-Bil in any situation where the fuel will sit more than a couple months.

The only fuel-related issue I can recall that might be similar to what is described is that a rubber bladder eventually disintegrated in my garden tractor's fuel pump when it was about 12 years old. But that could just have been pure age.

I certainly agree that old fuel can gum up fuel systems if left untreated, but ethanol blend doesn't seem to be bad on its own if kept fresh or treated with Sta-Bil.

Rob

 

If ya haven't tried it, don't profess to know what will happen. Try it, place about half a cup in a couple of containers, put an oz. of ANY ethanol treatment in one, leave them open to the air and see what they look like after a month.


We actually ran this over a the course of five or six weeks in a continuing education, night ASE class I first taught about four years ago. Unless you have magic ethanol gas in Minn., there will be a distinct difference...