91 octane gas in R/T model?

I was wondering if putting 91 octane into an neon R/T (2K3) is better than 87. Will I feel the difference? R/T model recommend 91 octane gas (in the manual and inside the gaz cover it's written). Will the PCM detect witch gaz is used and will auto adjust fire timing or putting 91 octane is a waste of money?

unless you have really high compression or a turbo its not gonna make a diff. It may run a little smoother but you prolly arn't gonna see any real diff.

unless you have really high compression or a turbo its not gonna make a diff. It may run a little smoother but you prolly arn't gonna see any real diff.When I put 91 or 93 octane in my 99 DOHC Sport, I see better acceleration and MPG. You don't need high compression or a turbo to see added benefits in the neon using a higher octane. Regardless, I would use whatever your owner's manual recommends, magert.

When I put 91 or 93 octane in my 99 DOHC Sport, I see better acceleration and MPG. You don't need high compression or a turbo to see added benefits in the neon using a higher octane. Regardless, I would use whatever your owner's manual recommends, magert.


We don't get 93 in cali :frown:

When I put 91 in my '98 R/T, it makes about 4mpg difference. I found that it is actually cheaper to put 91 in it b/c of the increased mileage. The Dohc's lose 4-5hp running 87 octane vs the 91 that is recommended. Although the '96-'99 Dohc's are rated 150hp they are actually 146HP (4 HP less than 95) due to a cam change. If you use 87, you lose another 4HP putting you at 142HP. If you run a SOHC and a DOHC (running regular fuel) side by side, there isn't hardly any performance difference. On the Dyno I have seen the SOHC at 110 (road HP) and the DOHC at 115. The DOHC puts out a lot more low RPM torque when you use 91, if you use 87 the Computer has to compensate by adding more fuel (for cylinder cooling) and retarding the timing (less power) that is why you see a low RPM power loss and less mileage.

Thanks for all yours answers. From my side, when I put 91 octane gaz I feel the car more agressive.. and engine noise is smoother! I will continue to use 91 octane gaz.. I don't know why but in winter car starts is better. !

91 will just allow the computer to advance the timing a couple more degrees without detonation.

Your engine will not suffer from 87 seeing the knock sensors will pick up any problems and adjust accordingly.

From my experience, 87 from a quality station will be better fuel than any 91 from a small generic station.

Just FYI.

When I put 91 or 93 octane in my 99 DOHC Sport, I see better acceleration and MPG. You don't need high compression or a turbo to see added benefits in the neon using a higher octane. Regardless, I would use whatever your owner's manual recommends, magert.

I agree!!! I see more miles per galon every time I use 93 or 91 octane. I might ad that I also think I get more responce from the car when I hit the gas. I think because the neon is controled by PCM it advances the spark.?? Don't know....., but I do know that it runs better and I make less trips to the gas station.

When I put 91 in my '98 R/T, it makes about 4mpg difference. I found that it is actually cheaper to put 91 in it b/c of the increased mileage. The Dohc's lose 4-5hp running 87 octane vs the 91 that is recommended. Although the '96-'99 Dohc's are rated 150hp they are actually 146HP (4 HP less than 95) due to a cam change. If you use 87, you lose another 4HP putting you at 142HP. If you run a SOHC and a DOHC (running regular fuel) side by side, there isn't hardly any performance difference. On the Dyno I have seen the SOHC at 110 (road HP) and the DOHC at 115. The DOHC puts out a lot more low RPM torque when you use 91, if you use 87 the Computer has to compensate by adding more fuel (for cylinder cooling) and retarding the timing (less power) that is why you see a low RPM power loss and less mileage.


I have seen simular results with my 98 DOHC sport. Funny thing is that gas is costing about twice as much as 5 years ago, but the cost differance between 87 and 91 is still the same, about 18 to 20 cents per gallon. Back when 87 cost $1.20 and 91 cost $1.40, 4 more MPG would just about cover the added cost. Let me illustrate:

If 87 Octane gas cost $1.20/gal and 91 Octane cost $1.40/gal, and the MPG went from 21MPG to 24.5 MPG (increase by 3.5 MPG), then look at what 10 gallons does:

87 Octane: cost $12.00, takes you 210 miles, or 5.71 cents per mile
91 Octane: cost $14.00, takes you 245 miles, or 5.71 cents per mile

So the cost per mile is about the same with premium.

Looking at today's prices in my area: 87 Octane gas cost $2.40/gal and 91 Octane cost $2.60/gal, and the MPG would still go from 21MPG to 24.5 MPG, then look at what 10 gallons does:

87 Octane: cost $24.00, takes you 210 miles, or 11.43 cents per mile
91 Octane: cost $26.00, takes you 245 miles, or 10.61 cents per mile

That works out to be 7% cheaper per mile traveled with Premium! I am making the assumption that a 3.5 MPG (15%) increase in MPG will really happen. If the increase is only 2 mpg (10%), then the calulations are differant. I do know that my milage dropped when I started using 87 last year.

When I put 91 or 93 octane in my 99 DOHC Sport, I see better acceleration and MPG. You don't need high compression or a turbo to see added benefits in the neon using a higher octane. Regardless, I would use whatever your owner's manual recommends, magert.

das the 96-99 dohc call for 92 or better stock so it will run better with the correct octane.

das the 96-99 dohc call for 92 or better stock so it will run better with the correct octane.I know, but just don't spend the extra money on the higher octane. My round trip to work and home is about 6 miles, so I don't think the higher octane is that much of a benefit.

Also, higher octane fuel burns colder and could lead to even worse economy in the winter seeing the combustion temperatures will be lower.

Higher octance fuel is only really needed in the summer.

The cold weather always keeps the engine running cooler than usual anyways.

I won't buy premium b/c I would get more power and better gas mileage and make my gas bill cheaper?

That it not logical.

Someone saying you get 4mpg more with premium fuel has got to be joking.