Looking at the manual, the recommended gas for the car is mid grade (87) and with it I am getting 21 mpg but when I use premium I seem to get 23. Is there a problem with running a higher grade gas?

8/3/2005 8:05:16 PM

never

8/3/2005 8:05:46 PM

holy shit

8/3/2005 8:28:22 PM

ethanol & watch it drop

8/3/2005 8:29:20 PM

nitromethane!

8/3/2005 8:53:57 PM

Any difference you think you're getting with premium is all in your mind.

Unless you have a lot of miles on your car, stick with 87. If you have over 150k then I'd use 89. But thats it, don't waste your money.

8/4/2005 7:49:44 AM

I always put 89 in my first car, and 89 Taurus GL with the same 3.0l "vulcan" V6.

I didn't have any problems with mileage, but I did with the tranny, brakes, tierods, cooling system, eletrical system, tranny again, alternator, idle, power steering, and "insta clear" windshield.

8/4/2005 7:53:09 AM

only reason i say to maybe put 89 in it if you have high mileage is b/c of the chance of carbon build up inside your combustion chambers raising your compression ratio (and creating hot spots) increasing the likelihood of pre-detonation causing knocking.

8/4/2005 9:37:02 AM

i have a gas related question also - is there any harm in mixing gases - putting in high grade then filling up with low grade when you have half a tank left of the high grade - does gasoline mix or do the different grades have different densities

my very limited understanding of gas is that different grades cause the chemical reaction that occurs to happen at a slightly different time - if you use the wrong grade for long enough the pistons will knock because the "explosion" is going off at the wrong time - i'm sure this is probably wrong/simplified - so educate me

8/4/2005 10:15:20 AM

My parents have a '98 Mercury Sable with the same engine - 3.0 pushrod V6 - it actually does stumble/occaisionally knock (or as much as the sensor will let it) on regular grade gas. They have to use midgrade.

And no, using a differnet grade gas will not affect milage.

And yes, you can mix different grades of gas without harm.

[Edited on August 4, 2005 at 11:55 AM. Reason : asfd]

8/4/2005 11:54:09 AM

Mixing different grades just dilutes the higher grade. For example, 89 octane is just 93 diluted with 87.l

8/4/2005 12:27:05 PM

Thanks for the help guys! I'll go back to mid grade. Regular will not work in the car, whenever we put that in it the gas mileage drops drastically.

8/4/2005 8:41:34 PM

Quote :

"Any difference you think you're getting with premium is all in your mind."

Im sorry Pat, thats just not right.

8/4/2005 9:09:50 PM

basically, the only thing premium is more effiecient in is high compression engines, some low compression engines can get more power and mileage from low grade

8/4/2005 9:16:24 PM

Quote :

"only reason i say to maybe put 89 in it if you have high mileage is b/c of the chance of carbon build up inside your combustion chambers raising your compression ratio (and creating hot spots) increasing the likelihood of pre-detonation causing knocking."

My '82 Malibu (only ~100K miles, but old and not well cared-for) was *much* happier on 89 than on 87. Ran much smoother, and mostly cleared up the dieseling after shutoff. If I put 87 in it would go back to bad habits in a hurry.

8/5/2005 12:00:33 AM

^That would call for a quart of tranny fluid poured slowly down the intake while revving to 2k rpms.

Sounds like a carbon issue to me. Not uncommon on one of those shitboxes.

I'm gonna run the cheapest thing I can score. If she pings a hair, I just bump the dizzy back a hair.

8/5/2005 12:02:54 AM

^^and why not. The best fuel for his engine is the fuel its designed for, which in this case is 87 (this is ignoring the mileage and build up possibilities)

Quote :

"And no, using a differnet grade gas will not affect milage."

It can affect mileage negatively if you use a fuel grade that your engine is not designed for.

8/5/2005 12:04:22 AM

On a related note, what are the current gas prices in Raleigh now? When I moved up here I could get premium for $2.41. Up here in Queens its currently between $2.71-2.81 at the nearest stations

8/5/2005 12:09:35 AM

$2.25 in gso.

gas prices are killer in ral.

8/5/2005 1:28:13 AM

$2.23 in Nor Ral

8/5/2005 9:15:36 AM