I know this has been beat to death,but still interesting.(sorry if I offend anyone)



Premium gas gives more power to high performance cars. They can move faster when you need it. These cars are designed to work their best using premium gas, but most of them don't require premium gas. Edmunds.com had an interesting legal point: if the car company said it was okay to use regular gas for a high performance car, the slight reduction in normal performance might make them liable if an accident occurred. So, they never say that it's okay. They just say recommended.

This really makes little sense because for several decades, cars have been outfitted with computer controlled, fuel injector systems that compensate for various octane conditions. Naturally, the car will perform best at the desired octane. Ironically, the fuel injectors also allow for manufacturers to design supercharged performance cars (which need premium gas).

Essentially, there are two reasons to choose premium gas at the pump.

The first: your car's engine experiences knocking. Older cars may have developed engine deposits that can cause more knocking. Also, in a modern car, you may experience knocking if you try going from premium to regular gas. In both cases, using premium gas may improve your car's performance. If the problem remains, get a competent mechanic to give your car a checkup.

The second: your car's manual says that it requires premium fuel. If it says that, only use premium fuel. Extended usage of regular fuel might save you some money at the pump, but, since the car was designed to work using premium fuel, you might pay more to keep it maintained. Not a good tradeoff!

To summarize, if you're okay with less power, you can use regular fuel as long as your car manual doesn't require premium. If you hear knocking noises, Car and Driver Magazine recommends that you should use premium gas and maybe invest some money in car maintenance, like a tune-up.

 

"you might pay more to keep it maintained. Not a good tradeoff!"

I would love to hear the explanation on that one.

Well I guess you could crack a piston if that is maintenance, otherwise??

 

From premature failures due to using regular and having the various sensors that control knock to have to be constantly regulating and working. Just think of a police office who works Beverly Hills and an officer that works East L.A. The one in 90210 is chilling, rolling along not doing much in his cruiser and retires full pension in 15 years. The one in East L.A. walking the street is probably going to encounter four or five incidents during his career, if he even survives.

Same thing, if you use premium stuff and the engine is running better and the sensors are not on overdrive all the time, then they'll last longer. If they're constantly working, then they're likely to fail more. O2 sensor $60, knock sensor $50, MAF sensor $60... and all this just parts cost.. just on and on. Although, I figure that you'd probably still save money using regular if say these components fail around 90K, at 20 mpg average over that mileage, you would have needed 4500 gallons of gas. At $.20 difference between regular and premium that would be $900 savings in fuel. You'd probably break even, unless you went to a Lexus dealer to get those things fixed.

 

I don't know, I have a hard time believing that the sensors on a car wear out from "use". O2 sensors don't care if you are a little rich or a little lean. If your mix is off enough to foul them that's one thing, but other than that an hour/mile of use is an hour/mile of use. I have never heard of knock sensors wearing out because they were detecting knock to darn much. I could be wrong but those things die randomly, some go 150k miles without a hitch and some die at 20k mikes for no reason at all. As long as you are not fouling plugs and carboning up the motor I would think maintenance is the exact same running 87 or 94 octane.

 

All I know is that there is a report to show anything you want in this world. One report will show that premium is good, one will show has no effect, one will show transfat is good, one that transfat is bad... who knows.

One thing is fact, all grades of fuel have to have additives to maintain fuel component cleaning. I believe it's been federal law for a while now. So, using 87 doesn't mean your engine is going to all of sudden gum up and run like junk.

The reason the "what grade to fuel" discussion is constantly coming up is because there probably is no definitive proof one way or the other to use premium or not. For my LS and RX and I use it just because I "think" it will be better for the vehicles. For my Integra I use it because I see a 2 mpg average drop when I've had to use regular and I'd rather consume less fossil fuel than save money.

 

Here we go again with the octane discussion.
I just turned 150,000 on my second RX. I have always used regular mostly Delta (off brand). I did expirment with preimum in both my RXs and found no noticable difference in mpg or power. I have never had a valid CEL, plugs were changed @125K and looked like new, valve cover was pulled to check for sludge and none was found. At what point do you think I will start to see these premature failures from using regular 200,000?, 300,000?, or ?.

 

Its okay mik,easy their big guy.The board was getting a little stale,and I came across this.Thought i would share it with you guys.I hate to break it to you,but this discussion will never completely die any way. I believe mostly because fuel prices rise every summer.I know the old mentality if you can afford a Lexus,you can afford Premium fuel.Well be that as it may,Most people dont like to waste money unnecessarily either (my self included in that factor)

I have mentioned before on here,although it may have been a pm to someone,that mine actually gets .8-1.0 better mpg on regular (in the summer time). The power on the highway isnt their,but hey it can be a fuel savings for me if I want it.But,once the winter blend formulation comes out,its game over! no power on regular/mpg then.I`m really surprised you dont notice that difference in the winter fuel Mikey.

I`m only one state west of you,and I would think we both get pretty much the same fuel.Any way`s were all brothers & sisters here on Club Lexus,And I wish every one the best!,And if I can help any of you out their,It`ll be my pleasure.

 

I guess this will always be a active discussion for those of us who own vehicles like the RX that fall in sort of in between territory as far as octane goes. I am just reporting my actual experience with 2 RXs which seems in contrast to what others are speculating "might" happen.

 

Actually I like hearing the fact that you put over 150,000 miles on your RX with no issues related to fuel.It shows that we truely do have an option with these vehicles.And I especially like the way you described your spark plugs looking good at that millage w/regular gas as well.

 

I have a 2001 with 110K. My ex and I bought it at 40K from a lady who dumped nothing but off brand 87.

My ex put nothing but off brand 87 octane in it, she made me a deal I couldn't refuse so I got it and have been nursing it back to health for over a year. I had to replace the knock sensors at 109K. The engine ran better but there was still a hint of a ping on acceleration. I started using MMO and Seafoam with the 93 octane and that sound slowly subsided and is not gone.

So, for what it's worth.....

 

Thats what is so strange re; this blue! you have Mikey with zero problems on regular,and then here is your case on the opposite side of the spectrum.Maybe its due to using the off brand stuff? less detergents etc. Name brand fuels i.e Shell,Exxon etc. all have good detergents in all three grades.

 

I was thinking the exact same thing just before you posted. I always mention that I use Delta (off brand) because I thought it was about as crappy as it gets. It's a price leader here in NJ. Maybe it's better than I thought. If I add up all my past cars I must be close to a million miles on Delta.

 

I have used Delta,and Riggins fuel coming back from the Shore,and it seemed to work very well.Especially the Riggins gas,I got my best millage on that stuff.

 

I have read that there are not 100 different suppliers of fuel running around feeding stations. There are only a handful of suppliers and they basically add whatever formulation to the base fuel and that becomes Shell/Exxon/BP and add a little different formulation for Delta/Citgo/USGas, etc.

Really, I think it's hit-n-miss with cars and fuel. Hey, all these sensors are parts that themselves have variances in manufacturing. Maybe Mike got a good vehicle using bad fuel so equates to many miles. Then Blue got a bad vehicle, bad fuel, and so the sensor just happened to fail.

I just get premium for the two Lexus' because they recommend it. I get premium for my GSR because I have recorded differences.