PDA

View Full Version : New to Premium Fuel...



Northport
11-27-2003, 08:24 PM
OK...here is perhaps a stupid question.

My FX35 is the first car I have ever owned where the manufacturer recommends premium fuel. I've always driven cars with "regular".

Most gas stations seem to have three levels; regular, premium, and "ultra" or somesuch.

Should I just go with the middle one?

What will happen if I just put regular in? How will performance be effected?

Any advice is appreciated!

PeteFX
11-27-2003, 08:35 PM
For best performance, go with the highest grade....at least 93 octane.

Bobiam
11-28-2003, 10:48 PM
Although I do not have an owner's manual for an FX to quote, I'd bet that they state a minimum octane number to buy. Anything above that octane and you are supporting the nations major oil companies, but not doing yourself or your car any good. In fact, there are plenty of experts that will tell you that extra octane can cause you headaches. The higher octane makes fuel harder to ignite (hence less chance of preignition - pinging), so some cars may be slower starting when they use extra octane (but I'd guess that that problem is more common for the guy that burns ultra ultra in a car rated for regular).

PeteFX
11-28-2003, 11:26 PM
......what the heck are you talking about?!

96_ss
11-29-2003, 12:28 AM
Although I do not have an owner's manual for an FX to quote, I'd bet that they state a minimum octane number to buy. Anything above that octane and you are supporting the nations major oil companies, but not doing yourself or your car any good. In fact, there are plenty of experts that will tell you that extra octane can cause you headaches. The higher octane makes fuel harder to ignite (hence less chance of preignition - pinging), so some cars may be slower starting when they use extra octane (but I'd guess that that problem is more common for the guy that burns ultra ultra in a car rated for regular).



Exactly...Don't waste your money on premium, except when it states "for best performance".

You can try mid-grade, and if you don't get any knocking, keep using it. When it makes a difference is when you have heavy loads, or steep roads, or something that puts a heavy load on the engine.

....And in California, we have 92 not 93.

Northport
11-29-2003, 08:48 AM
Let's say I'm a cheepskate, and put regular in my tank instead of premium.

What, specifically, might I notice about my FX35's "performance"?

DJLFX
11-29-2003, 08:57 AM
Consequences of using lower octane gas:

If knock sensors detect knock, the ECU will retard timing to minimize it in order to prevent engine damage. This will reduce horse power and torque. For FX35, the manual states that premium gas is "recommended".

DJLFX
11-29-2003, 08:58 AM
Consequences of using lower octane gas:

If knock sensors detect knock, the ECU will retard timing to minimize it in order to prevent engine damage. This will reduce horse power and torque. For FX35, the manual states that premium gas is "recommended", not required.

FX35POWER
11-29-2003, 10:19 AM
there was an article in car & driver magazine comparing the effects of premium gasoline (91, 92 or 93 octane in my area) to regular gasoline (87 octane).

in our case, infiniti/nissan recommends "premium" gasoline ...because the engineers designed our engines to extract all the power possible from this grade of gasoline.

regular gasoline can be used, as the sophisticated electronics will compensate for regular grade gas to prevent knocking BUT there will be a decrease in hp and torque and according to the article a possible decrease in miles per gallon.

(as an aside, they also concluded that a car designed for regular gasoline will not benefit from premium gasoline as the engine is not designed to extract the additional "power" of the higher octane gasoline. this IS a waste of money.)

the issue i have in my area (ne us)is that mid-grade gasoline with 89 octane is available. i have filled up with this several times in a few different cars/suvs including mb ml320, acura MDX and one tank in my FX45 and i did not notice a difference in performance---BUT relying on how performance FEELS is not very reliable.

i have decided that since i chose to own an FX45 specifically because of its great engine/performance(or to FX35 owners, since infiniti recommends premium gasoline in both engines) i will spend the extra few dollars on premium gasoline.

IMHO, it doesnt make sense to drive a sophisticated, world-class performance-oriented S2UV and use anything other than premium gasoline.

kenny_crudup
11-29-2003, 11:16 AM
since infiniti recommends premium gasoline in both engines)


Well, in the case of the '45, it's actually required (probably due to the 10.1:1 compression ratio).



IMHO, it doesnt make sense to drive a sophisticated, world-class performance-oriented S2UV and use anything other than premium gasoline.


Well, only if the car can compensate for it (as the '35 can). Otherwise, you're just wasting your money. I just found out my GF's daughter was putting 91 in her '95 normally-aspirated Eclipse; had to larn-'er otherwise.

EffEcks
11-29-2003, 01:56 PM
It's not about additional "power" in high-octane gasoline, octane is a rating of how much a given fuel can be compressed before it spontaneously combusts. In a high-compression motor you want gas that's more stable (harder to burn) so that the charge doesn't iginite spontaneously before the spark plug has a chance to do it's job. If you put this same fuel in a car with a low-compression motor the engine won't be able to fully burn it and you end up wasting gas out the exhaust and may also get unburned fuel deposits in the motor.

FX35POWER
11-29-2003, 03:59 PM
kennykrudup...
probably most, if not all, modern engines that are recommended to run on premium CAN run on regular gasoline because their electronics can compensate, but according to the car & driver article the end result, in most cases, is less power and reduced miles per gallon.

EffEcks...
i agree with you and this is why "power" is written with quotation marks. according to the article the octane correlates to the % of isooctane in the gas (the remaining % is composed of n-hexane). isooctane is more stable, a characteristic that is desireable, as EffEcks pointed out.

kenny_crudup
11-29-2003, 09:29 PM
kennykrudup...


(How do ya mspiel my name when it's right there in front of ya?!)



probably most, if not all, modern engines that are recommended to run on premium CAN run on regular gasoline because their electronics can compensate


Yeah- but that's the opposite from what was happening to what's-her-face- her car was spec'ed for 87, and she was running 91 in it 'cause (thanks to good marketing, I guess) she thought it was "better".