87 Octane Vs 93 Octane, what's the big deal?

[v8Toilet]

I read my owners manual and Toyota recommends 87 octane or higher unleaded gasoline. The Lexus version of our motor requires 91 octane fuel. My truck seems to run better on 93 than it does on 87. With 87 Octane I can hear it momentarily ping on hard acceleration and my gas mileage goes down slightly.

Anyway I usually put 22 gallons of fuel into my tank. Regular costs $1.47 and the 93 octane costs $1.59 here in Massachusetts. The difference in price when filling my tank with 87 Vs 93 octane gas is $2.64. I can't believe people make a big deal over such a little difference in price when they drive a 20-30 thousand dollar vehicle. Don’t forget you get a few more miles out of the higher octane gas because the computer isn’t retarding the timing to reduce the pre-ignition or detonation, which reduces fuel economy.

[KLS]

Here in western Washington the price difference is 20¢ to 30¢ per gallon--and 91 or 92 is the best available.

I don't think that the momentary ping is a problem. A very slight ping might be the correct spark timing and no harm to the engine.


Ken

[thekurgan]

I've never heard any type of pinging with the 87 octane stuff. I replaced my plugs at 15k (have 18k now) and use the stock denso plugs gapped at .032. Could there be some other reason you're hearing the ping such as an O2 sensor going bad? Just a thought. I'll give a higher octane gas a try my next tank, see what happens. With a low compression head, I wouldn't think that anything higher than 87 would be necessary.

[Genthar]

Out here in CA, the price difference can also be $0.20-0.30/gal. between 87 and 91. Unscientifically I once tried a couple of tanks of regular, a couple of tanks of midgrade, and a couple of tanks of super, and my mileage went up with midgrade, and down with super. Of course this wasn't a very controlled experiment, as the weather may have changed, my driving style may have changed, etc.

[Sumo99]

I fill up at least once a week. Lets be conservative and say I use 20 gallons/week, at $.20 more/gal for 91 octane (we don't have 93 around here). That's an extra $4/week multiply that by 52 weeks = about $208 more per year in gas. I'll save that $200 for extra toys for the Tundra.

[v8Toilet]

Originally posted by Sumo99
I fill up at least once a week. Lets be conservative and say I use 20 gallons/week, at $.20 more/gal for 91 octane (we don't have 93 around here). That's an extra $4/week multiply that by 52 weeks = about $208 more per year in gas. I'll save that $200 for extra toys for the Tundra.

Let’s say I get 25 more miles per a week because I use the super instead of the cheap stuff. If I drive 52 weeks a year I would travel 1300 more miles and save 76 gallons of gas or $121.58. So the extra cost of the super really costs me about $80 a year, that’s $1.54 per a week!

With a 9.6-1 compression ratio the Tundra isn't exactly a low compression engine either. I don't hear any ping what so ever with the 93 octane even momentarily.

[Boone]

I've always filled up with premium gas (never at Texaco). 24 gallons at $1.66 this morning. Gets expensive but piece of mind for me.

[Forester]

I typically get 19 mpg on 89 octane. I thought 89 was the recommended.

I calculate the mileage every time I fill up (actual mpg, not miles per tankful).

After seeing this thread, I checked the owner's manual and by golly as others have said, the manual says it will run better on higher octane.

I had noticed a little sluggishness on a grade I drive quite often.

Filled up with 91 octane (10 cents more/gal.) and it really does run better. If the engine is retarding the timing to prevent pinging, then that should affect how it pulls that grade, how it accelerates and reduce my mileage.

So I bring up Excel and it turns out that if 91 octane gives me only 1/4 mpg better mileage, it will cost me only $28 per year more for gas. If there is no improvement, it will cost me $58 per year more. But if I get 1/2 mpg better on the 91 octane, I'll be $2 per year ahead.

We'll see!