klumzypinoy
New member
I use Costco gas most of the time. So, why shouldn't we put 91 or 89 into a car that uses a minimum of 87 octane? I notice the fuel goes down fast on 87 and goes down slow on 91.
"Cheap" gas v. Cheap gas
- Thread starter imported_truzoom
- Start date
klumzypinoy said:
higher octane gas doesn't burn any better, it actually burns slower, which is why you don't see any benefit unless your car is tuned to take advantage of the slower burn. It won't hurt your car to run a higher octane than what you require, but any benefits are in your head.
topnotchtouch
New member
JDookie said:
Actually the state and federal government mandate that a certain level of cleaning additives have to be added to ALL gasoline. The major brands though use more than the minimum and they all have their own special additive recipes.
topnotchtouch
New member
JDookie said:
Actually the federal government (epa) reguires a certain level of detergents in ALL gasoline.
Gasoline Fuels - OTAQ - EPA
truzoom said:
In general - gas is gas. BUT..., and isn't her always a BUT? The detergent and solvent packages added to top tier gasolines can have a positive effect on cleaning injectors, lubricating fuel bladder sensors, and minimizing deposits. I can tell you that years ago, when we tore down an engine, we saw lots of crud on valves. Mostly lead, I think. Today, even the dirtiest engine is very clean indeed in comparison. I think that performance related engines with high compression ratios can benefit from top tier gasolines with higher octane ratings. For those with engines designed to run on 87 octane - save the money.
Corey Bit Spank
Active member
cole said:
Well, these additives will likely increase the octane rating. Ergo, the additives will allow the gasoline mixture to burn more like ideal 2,2,4-trimethylpentane. So, if "better" additives are added (how are we defining better? better solvent? burns more evenly?) then eventually we won't have 93 octane.
codiddy said:
(I read up a LOT about 3 years ago when I had what I considered a performance vehicle rated for 87 octane and someone told me I was wasting my money and crudding up my car by putting in 89 octane to "give it a treat" so to speak.)
From what I've always read, the octane rating of your car is based on how the engine is tuned and what compression ratio the engine has. A regular car that is tuned for "regular unleaded" means that it runs perfect with 87 octane. Lots of performance vehicles require premium and some race tuned cars require even more than 93 octane and have to get race gas.
Two main things you need to understand is 1) how car engines work and 2) a little bit of chemistry regarding octane.
Car engines are considered four stroke because there are four stages:
1) intake -- gas enters the cylinder through the intake valve(s)
2) compression -- the piston moves upward and compresses the gas in the cylinder
3) ignition -- the compressed gas ignites c/o spark plugs
4) exhaust -- the piston moves back downward and the exhaust gases leave through the exhaust valve(s)
You can look online and find the required temperature/pressure combination for certain levels of octane to ignite. The higher the octane rating the fuel has, the higher the temperature/ pressure that's needed to ignite the fuel.
Gas with higher octane rating than needed (89/91/93 in a car that needs 87) is a waste because the engine doesn't fully ignite all the fuel (engines meant for 87 don't have enough compression to fully ignite the higher octane), so you actually have unburned gas going straight out your exhaust (which I'd assume would put more strain on your cat. converter too) OR crudding up your engine.
A high performance car that the manufacturer REQUIRES premium gas actually results in a "knock" in the engine because the car is set up to compress and properly ignite 91/93 octane, so putting 87/89 into the engine results in the compression alone (stage 2 above) igniting the fuel instead of the spark plugs igniting it properly (stage 3 above). Because the gas ignites early, the timing of the engine gets really messed up and you have all sorts of other problems that your mechanic has to fix which costs FAR more than the 10 cents/ gal you should be spending on your PERFORMANCE vehicle.
Overall, the message is to fill up with the octane rating your car NEEDS -- no more, no less or you're either totally wasting money (which everyone complains enough about gas prices... why pay more and create problems?) or you're wrecking your engine.
Any questions, PM me.
To be fair, though, I think the ECU on modern cars can adjust the timing to compensate for a using regular in premium. However, I know it doesn't work the other way around (i.e., a 87 car won't advance timing if you stick in 91).
But I know that only works for N/A engines (mostly). If you're running F/I, then absolutely, do not make the mistake of getting regular! lol.
However, even though I said that, I'm a firm believer that you should be pumping the appropriate gas for what you bought. If you spent $35k+ on a car and are trying to save a few bucks at the pump by pumping regular... maybe you bought the wrong car.
But I know that only works for N/A engines (mostly). If you're running F/I, then absolutely, do not make the mistake of getting regular! lol.
However, even though I said that, I'm a firm believer that you should be pumping the appropriate gas for what you bought. If you spent $35k+ on a car and are trying to save a few bucks at the pump by pumping regular... maybe you bought the wrong car.
klumzypinoy
New member
paul34 said:That's because your car is lighter due to the reduced amount of money in your wallet for no reason
LOL thanks
hahah.Well after reading Jon54956's post, I understand now.
Inside my gas door, it says Premium recommended, really weird for my 1992 Galant GS, I mean it's not a VR-4 :chuckle:
Perfect Touch
New member
i never look at price. always Shell V-Power for my VR6.
robertrinaustin
New member
I have a very high horse power car and can guarantee there is a difference between cheap gas and quality gas and have measured this on the dyno. Shell premium produced almost 20 more whp than Diamond Shamrock (now Valero). For whatever reason, the cheap gas is more knock prone and this reduces power as well as other more serious problems associated with knock. My guess is that the better quality gas has a bit higher octane, but that is only a guess.
If you have a high hp or highly tuned car, I would strongly suggest you run quality gas or you may be giving up some power. I've noticed this in cars ranging from a Mazda Miata to a twin turbo Porsche and the problem is worse in the hotter months.
The other interesting thing I've measured is not all stations of the same brand have the same quality gas. I like Shell, but there is one in a small town not too far from where I live that has the worst gas I've run. A friend and I have both experienced problems with this Shell. I have a turbo car and reduced my boost by 3 psi (from 24 psi to 21 psi) and dropped 3 degrees of timing from my regular settings and was still knocking like a front door on Halloween.
For my car, I am currently running 100% e85, but before that, I only ran Shell, Chevron, Texaco or Exxon. I regularly used Diamond Shamrock until that day on the dyno.
If you have a high hp or highly tuned car, I would strongly suggest you run quality gas or you may be giving up some power. I've noticed this in cars ranging from a Mazda Miata to a twin turbo Porsche and the problem is worse in the hotter months.
The other interesting thing I've measured is not all stations of the same brand have the same quality gas. I like Shell, but there is one in a small town not too far from where I live that has the worst gas I've run. A friend and I have both experienced problems with this Shell. I have a turbo car and reduced my boost by 3 psi (from 24 psi to 21 psi) and dropped 3 degrees of timing from my regular settings and was still knocking like a front door on Halloween.
For my car, I am currently running 100% e85, but before that, I only ran Shell, Chevron, Texaco or Exxon. I regularly used Diamond Shamrock until that day on the dyno.
imported_Larry A
New member
Since ive been useing Shell gas which is the only Top Tier gas you can get here, my gas milage has gone up 2 miles per gallon.Ive had my car 6 years and I averaged 20 mpg in the city, now its 22 mpg city mileage. That is the only change ive made useing Shell.