Myth's about Premium Gasoline

[SpankyPop]

I don't understand how people can "feel" the diffrence between using 89 octance gas and 92/93. There is no way your butt dyno can tell the added gain from something that dosen't add anything. There are not more BTU's of energy in premium gas than there are in regular or mid grade. Its all exactly the same gas, but some has some additives in it to help it resist knocking. My Honda Integra GS-R has a compression ratio of 10.0:1 I could probably get by on mid grade or regular on cold days, or if I was in an area higher in elevation. Otherwise, you MUST use premium gas for anyhting over 10:1 compression. If you don't detonation will kill your engine. Nice article, by the way, dave.

[moolman]

Premium gas does not have more additives than regular. How do I know this, I'm majored in both Chemistry and Chemical Engineering at the University of Southern California. I interned at the Chevron refinery in El Segundo, CA for 2 years. The only difference between the different grades was how much of an octane boost chemical it got. (i forget the name) The amount of techron put in it was equal because all the refined gasoline started from the same tank. I talked to my boss who worked in the gasoline refinery business for over 20 years. He told me it costs them next to nothing to make premium gas over regular. Also did you know that gasoline companies routinely share gasoline. For example, if unocal 76 was running short on gasoline, they would borrow some from Chevron and vice versa all the time. Not ocassionally, but all the time. The additives didn't really make a difference because by California law or maybe even federal law there had to be additives like detergents and oxygenates in it and they were basically the same. They even had a joke in the office about how premium was such a scam for people and how all the gasoline does is boost profit margins.

The only time premium gas makes a difference is when your car needs it. If your car says to use premium gas, you must use it or your car will be retarded by the ECU and will lose horsepower. When your car requires regular and you use premium, you get nothing out of it but wasting your money and probably hurting performance ever so slightly because the timing in your car isn't calibrated for the less volitile (higher octane) gas. There are no extra detergents, your engine is just as clean or just as dirty from using premium or regular.

One recent car that calls for regular but does get a boost from premium gas is the 2003 honda accord V6. Now why does this car get a boost from premium. Honda designed it so it runs on regular with knock sensors and if premium is used, the timing is advance by the computer until the knock sensors sense Knocking. So you get about a 10HP boost. This is not the norm. Most cars do not have a computer that will advance the timing, only this car and the pre 2002 Honda Oddessey are the cars I'm aware of.

A car like the BMW that requires premium has the timing advance already like the Honda accord would do but it get retarded or set back when regular is used.

SO bottom line, save your money and use regular unless you drive a car that needs it or a 2003 accord v6 or the pre 2002 oddessey.

forgot to mention. If your car doesn't require premium and you use it and you feel you get better mileage or a boost in power, I have some ocean front property to sell you in Nevada. Please email me ASAP.
Alex

[YoSteve]

The salesman told my dad specifically NOT to use premium gas. I think it says somewhere in the manual why not to. I'll guess, I'll have to check when the Bravada comes back from the shop.

[wilbanks]

What an interesting thread! It sounds like we have some pretty savvy car people here.

For what it is worth here are some more thoughts:
According to the Wall Street Journal yesterday's spot prices were:
Premium non oxygenated gas $.9078/gal
Regular non oxygenated gas $.8678/gal
Difference $.0400/gal

It is easy to see if you need premium. If you use regular try a tank of premium and see if your car runs better. i.e. better acceleration/less knocking. If you use premium try a tank of regular and see if you get less acceleration or some knocking.

The only difference I know in regular and premium other than octane is with Mobil Premium. It has a detergent in it. I run a tank through now and then since it is easier than buying a bottle of gas line cleaner at Auto Zone.

[moolman]

hey,
Like I stated before, ALL yes ALL gasoline grades have the same amount of detergents, even Mobile regular Vs premium. It's just that they don't advertise it so that people are fooled into thinking that only premium has it. Call mobil, call chevron, ask them if their regular has the same detergents as premium, they will say yes. It's more expensive for them not to put the detergents in because the refining process would have to be altered just for that. Besides, it's state law, should be all states that detergents and oxygenates are used to lower pollution.

Alex

[Green Monster]

When you put an after market computer chip in (Super Chip or Jet Chip) they say to run Premium gasoline, is true or just a marketing thing??? Any thoughts?

[medic]

Originally posted by Green Monster
When you put an after market computer chip in (Super Chip or Jet Chip) they say to run Premium gasoline, is true or just a marketing thing??? Any thoughts?

Most (all as far as I know, but I'm sure there are some strange ones out there) either alter the transmission shifts or the settings the ECU accepts from the air flow sensor, O2 sensor, etc. I would probably go with premium gas if that's what they reccomend since the chip has altered what is mixed together in the engine.

[Redcar GUY]

I know my friends wife put 87 in his camaro one day by mistake, needless to say the car didnt run right for 2 or so tank fulls. I use the best in the SS I can get and 87 in the Cav/satty

[blkZ28Conv]

Originally posted by medic
Most (all as far as I know, but I'm sure there are some strange ones out there) either alter the transmission shifts or the settings the ECU accepts from the air flow sensor, O2 sensor, etc. I would probably go with premium gas if that's what they reccomend since the chip has altered what is mixed together in the engine.

Many of these chips / ECU reprogrammers advance the timing about 2-3 degrees. This is why they recommend premium fuel. An insurance against advance induced detonation.

[moolman]

If you get a chip installed, you have to run premium because the chip is advancing the timing just like the 2003 accord V6 I was talking about before. So yes, you have to use premium or you might get knocking.

If you're using an old car that states in the manual to use regular but now that it's like 10 years old will only run good on premium, that is because of build up or some other problem in the engine, the premium is only masking the problem of the engine but in this case I would use premium until the car died because at this point for an old car it's not worth the expense of fixing the engine. Now for a newer car that is suppose to run on regular and starts pinging/knocking you better have a mechanic check it out cause by using premium to hide the knocking your just putting off a repair until later when you'll probably have to pay more for it.

Alex

[Neb]

My car actually gains a few hp from using 93octane instead of 91. most people's opinion are that Honda designed our motors to run with what was available in japan, which is 93. But California just has to only have 91

[2000_EBP_civic]

Originally posted by Neb
My car actually gains a few hp from using 93octane instead of 91.

Do you have dyno charts to prove that or are you just using the butt dyno?