89 to 87

[cluv]

I have been running 89 octane(mid-grade here in Texas) since I bought the car in May '04. With the gas prices increasing, I was thinking about changing to 87 octane(lowest grade in Texas) to save a few bucks here and there, but I have a couple of questions.

Will doing this change harm the engine in any way? You know, since the engine is already "used" to the mid-grade?

Will it affect performance at all?

I know those are some silly questions, but I'm not the biggest "Motorhead" in the world. Just looking for some advice.

Anyone?

[COLORADOMAGNUM]

87 is mid-grade in Colorado. I have been running it in my SXT since new. It runs great, no pinging or knocking. In my opinion, you should be just fine.

[Stonebreaker]

Modern cars are smart enough to pull timing when the engine starts pinging. You sacrifice power, but as long as the computer is stock you should be OK.

[boggart]

When I go from 89 to 87 my MPG drops significantly.

[mikeyb]

I'm running 87 octane in my RT. Can tell a slight difference in performance. Few weeks ago did a 2k mile roadtrip and got anywhere from 20-24mpg.

MikeyB

[desquirrel]

Highly doubtful to have a measurable mileage difference unless you get a really bad batch of fuel significantly off grade. No one here has ever done a mileage test using a method that is free from normal variations.

[cluv]

Thanks for all the info guys, I think I'll try a tank of the 87 next time I fill up and just see how it works. I guess I was just more worried about messing up the engine or something(I know that sounds stupid), because the engine had been used to the 89 for so long.

Thanks again for all your help!! That's why I love this forum!!:-)

[Padre Dave]

I usually run 87 in my R/T, and occasionally throw in a tank of 89. I find NO difference in power, but 87 gives me better mileage. So, why do I continue to occasionally buy 89? I'm asking myself the same thing.

[Banshee]

you only need high octane rating fuel if you have a higher compression engine.The higher octane keeps a high compression engine from knocking.(preignition)
A 10 to 1 engine will not run any better on 105 octane than it will on 89 octane. You are wasting you money by using a higher rating than what is required.

[boggart]

I don't know about you guys, but I don't need a "scientific" test to tell me that my car gets 3-4 MPG worse if I run 87 octane instead of the 89 octane called for in the owners manual. I understand why it doesn't make a difference in Colorado because of the elevation, but here in KS, it makes a BIG difference. I wish I had one of the lucky cars that it doesn't seem to make a difference in.

[snickle]

I have tried 87 a bunch of times and the mpg is always worse, by more than I am saving.

However, I think that has more to do with the driver than the car. I find myself giving it more pedal, to get the same responsiveness.

So for me, no advantage in 87.

[snwghst]

Makes no difference in Atlanta or on the gulf coast. I actually get better milage with 87

[cluv]

Just a side note...............................

I have an RT, who out of these posts has an RT?

[Padre Dave]

As noted, I drive a RT

[Dupie24]

another side note............
whats the deal with the gas mileage? Padre Dave gets better with 87, MagnumSXT gets worse, we need to know what kind of engine each person has, maybe that makes a difference. I have an RT and no change in gas mileage from 91 to 89 octane, seems to run ok on either. My gas mileage sucks, 10 mpg in town. Going a road trip this upcoming weekend, see what I get on the road