The Great Oil Change Discussion

[smooth1]

I don't know that I agree with it all being "hype". Dennis Decota was actually referring to the price of gas in California and the lack of wholesale competition. So when Top Tier appeared, he then refered to the "hype". I'm actually very familiar with Dennis Decota. I just read his 142 page report on why gas costs more in California.

The differences aren't in the gas itself, or where it comes from. The difference is the quality and quantity of detergents that are added to the gasoline AFTER it is in the US. ILFC Ten 32 for example is a compound composed of a dispersant, a biocide, a demulsifier, a corrosion inhibitor, and a polymerization retardant. And Techron, or Techroline, which was developed and patented by Chevron, is considered one of the best on the market right now. Your saying that some detergent combinations like ILFC Ten 32 is just as good, or makes no difference? And every different gas company uses a different detergent mix, ratio, and so on. these detergents don't make the fuel itself better, they just make it better for your car. The Top tier program was designed to unify the standard and give the auto mfgrs. a scale to measure against. After all, it's in thier best interest.

Top Tier

[nomad2009]

I filled up with regular this week and I am telling you it is lasting forever what is up? I filled with Exxon Regular I think its 87 Octane. The same exact miles to work and back the same mundane cycle every week except by thursday I usually need a fill and I still have a 1/4 tank, I am really blown away, how could this be?

[Knightshade]

I filled up with regular this week and I am telling you it is lasting forever what is up? I filled with Exxon Regular I think its 87 Octane. The same exact miles to work and back the same mundane cycle every week except by thursday I usually need a fill and I still have a 1/4 tank, I am really blown away, how could this be?

You get better mileage in warm weather for one

Summer gasoline has different contents in it too in case they changed over recently at your local stations.

There's plenty of other factors that impact mileage too.

But I can tell you that all else being equal it's impossible to get better mileage from lower octane fuel. There's nothing chemically inherent in lower octane that can cause that to happen. If your car is designed for 91 you will either get the same or worse with 87 if all else is equal depending on how much the ECU is having to adjust Problem is all else is virtually never equal.

In the meantime you're damaging your engine though.

Like I said, if you don't plan to keep the car a long time, and plan to lie to the next buyer, this won't be a problem for you, as the damage will likely take a long time to be apparent.

[nomad2009]

I filled up with regular this week and I am telling you it is lasting forever what is up? I filled with Exxon Regular I think its 87 Octane. The same exact miles to work and back the same mundane cycle every week except by thursday I usually need a fill and I still have a 1/4 tank, I am really blown away, how could this be?

You get better mileage in warm weather for one

Summer gasoline has different contents in it too in case they changed over recently at your local stations.

There's plenty of other factors that impact mileage too.

But I can tell you that all else being equal it's impossible to get better mileage from lower octane fuel. There's nothing chemically inherent in lower octane that can cause that to happen. If your car is designed for 91 you will either get the same or worse with 87 if all else is equal depending on how much the ECU is having to adjust Problem is all else is virtually never equal.

In the meantime you're damaging your engine though.

Like I said, if you don't plan to keep the car a long time, and plan to lie to the next buyer, this won't be a problem for you, as the damage will likely take a long time to be apparent.

how can 2 or 3 in octane be that much damage seems kinda weird, I am not convinced its as bad as you say. I without a shadow of a doubt am getting more mileage. The weather was the same temp so no major deviation.?

[nomad2009]

I filled up with regular this week and I am telling you it is lasting forever what is up? I filled with Exxon Regular I think its 87 Octane. The same exact miles to work and back the same mundane cycle every week except by thursday I usually need a fill and I still have a 1/4 tank, I am really blown away, how could this be?

You get better mileage in warm weather for one

Summer gasoline has different contents in it too in case they changed over recently at your local stations.

There's plenty of other factors that impact mileage too.

But I can tell you that all else being equal it's impossible to get better mileage from lower octane fuel. There's nothing chemically inherent in lower octane that can cause that to happen. If your car is designed for 91 you will either get the same or worse with 87 if all else is equal depending on how much the ECU is having to adjust Problem is all else is virtually never equal.

In the meantime you're damaging your engine though.

Like I said, if you don't plan to keep the car a long time, and plan to lie to the next buyer, this won't be a problem for you, as the damage will likely take a long time to be apparent.

how can 2 or 3 in octane be that much damage seems kinda weird, I am not convinced its as bad as you say. I without a shadow of a doubt am getting more mileage. The weather was the same temp so no major deviation.?

I am going toput the same brand premium and see.

[Knightshade]

it's at least 4 octane from 91 to 87.... and that's kinda like saying I don't understand how an A1C blood sugar of 11 can be that much worse than 7... but ask a diabetic. 11'll have you going blind and losing appendages in moderately short order, 7 is normal.

If the car is programmed with timing for 91 octane then running 87 will cause knocking, which damages the engine. The knock sensors detect the knock, and !Removed! the timing... if they didn't do that you'd need a new engine fairly shortly.

Then after a bit the computer adds timing back, because it's still programmed for 91 and has to assume the knocking was a fluke event, so it knocks again...the sensors see it, and the ECU retards timing again.

The retarding timing is why you have measurably less power with 87.

So thanks to the ECU and the sensors you're only damaging your engine a little at a time instead of killing it fairly quickly.

It's still a pretty stupid thing to do to save a whopping $2-3 a tank.

[bartkat]

The truth of the matter is that fuels with higher octane levels are blended to handle higher temperatures and pressures without pre-ignition.

http://www.stockcarracing.com/techarticles...burn_rates.html

[dallaslexus]

Like I said, if you don't plan to keep the car a long time, and plan to lie to the next buyer, this won't be a problem for you, as the damage will likely take a long time to be apparent.

I guess that's the beauty of a lease!!! I can save a few bucks with regular and don't have to lie to anyone!

[Knightshade]

Like I said, if you don't plan to keep the car a long time, and plan to lie to the next buyer, this won't be a problem for you, as the damage will likely take a long time to be apparent.

I guess that's the beauty of a lease!!! I can save a few bucks with regular and don't have to lie to anyone!

Sure hope the dealer never checks with the ECU and notices all the knock/!Removed! events... I'd imagine someplace in the lease agreement it expects you to maintain the car properly, which'd include the required fuel. I doubt they check, and it's LIKELY the engine won't be damaged enough in a couple years of a lease, but seems like a pretty stupid gamble to save $2-3 a fillup.

[JENunnez]

Really why would you risk alot just to save a few bucks.

17 gal.

Reg. @ 4.07 = $69.19

Prem @ 4.30 = $73.10

You save $3.91.

That's the price here right now. (Sonoco)

Wow what a saving!

[Knightshade]

Really why would you risk alot just to save a few bucks.

17 gal.

Reg. @ 4.07 = $69.19

Prem @ 4.30 = $73.10

You save $3.91.

That's the price here right now. (Sonoco)

Wow what a saving!

Not to mention it's entirely possible to lose mileage from the knock/!Removed! cycle so you don't actually save anything in that case

[Hutch]

I used mid grade in my 94 LS for over 50K with no knocking or any other probs

[Knightshade]

I used mid grade in my 94 LS for over 50K with no knocking or any other probs

That was a port injected V8 with a 10:1 compression ratio.

This is a direct injected V6 with a 12:1 compression ratio.

Not an especially useful comparison.

Not to mention, with modern knock sensors, you'd have no idea if the engine ever knocked or not unless you were running a real time data scanning tool on it. For all you know after 50k miles it had the wear of 100k miles. Not an issue if you got rid of it before it failed, but again I wouldn't want to be the next owner.

[BaddBoi70]

If you have the money to purchase a Lexus, then why would you NOT use the recommended fuel (91 or better octane) stated in the owners manual? Seems foolish to me just to save a few bucks at the pump. I compare it to the scenario of the guy/gal who walks into a Ferrari/Lamborghini dealership and asks, "How many MPG will I get with this car?" WHO CARES???? If you have to ask, then you obviously can NOT afford the Ferrari/Lamborghini. You should walk out the door and go down the street to the Ford dealership and buy the Mustang! Similar comparison, only walk out of the door and go down the street and buy a Toyota, which allows you to use the 85 octane fuels.

Seriously, if you fill up once per week and save a whopping $4 each time, then you save about $208/year. If you can not afford $208/year, then you should NOT have purchased a Lexus vehicle.

[JEFFREY ETPPER]

I am just wondering if anyone has religiously been using a lower grade than 93 octane in their IS250/350 and if they have noticed a difference in gas mileage/performance and or noticed any problems?

I have heard that you can use as low as 87 without any problems however I have also heard the opposite and the dealer states that the car might make some knocking noise's w/ lower octane.

It is understandable that you might get worse mileage with lower the octane but I was wondering if anyone has tried and had good enough gas mileage to make paying less worth it?

[

I own a 2008 IS250AWD.

I drove the car about 4,000 miles on Premium fuel. After finally reading the owners manual I tried 87 octane fuel. I have driven about 750 miles on Regular and have not noticed a difference in performance and there isn't any engine knock. My car runs as well on regular as with premium fuel.

[Knightshade]

You mean you haven't noticed any engine knock

Which means the knock sensors are doing their job.

You'd need something that read data off the CAN bus to actually -know- if you were knocking or not.

Given that lexus didn't just decide the car needs 91 to run properly for their health, you likely are.

In an AWD 250 though your performance is pretty poor to begin with, so you'd likely need to make an effort to measure what you're losing by the ECU pulling timing.

What you're losing in long term engine damage will take a while to notice.

But hey, you're saving $2-3 a tank, so there's that.

Well, assuming you've actually, scientifically, measured the mileage differences properly... since it'd take a pretty small difference to lose that 2-3 bucks back... a 5% drop in mileage would negate all the "savings" while still doing the damage and pulled timing.

[seohenning]

It has been a while since I chimed in on this topic, but I wanted to add a twist to the great debate. I have been driving the IS250AWD for almost two years now (for those out there who care on premium 98% of the time). So here it what I have found.

I drive about 30k a year almost all highway in NY. Winter of 06 I averaged around 26.2 MPG, then in the summer of 07 I was averaging 27.8 MPG! (Which was more than I expected). I had several tanks above the 28 MPG mark. As I expected that dropped a back down in the winter of 07 to around 26.0 MPG. Now with no driving changes or fuel etc... in the summer of 08 I am averaging 26.5, the only difference I have noticed is that I can't find any gas in NY without Ethanol in it.

Now with the "Corn Fuel" Ethanol being added to the mix seems to to have made about a 2 MPG difference since this was introduced as a viable fuel option. I don't have all of the facts and I haven't researched this and I honestly don't know if it makes a difference. I know the cars HGWY MPG is estimated at 26, but I can't imagine if I was consistently getting 28 last summer why it would drop coincidently with the introduction of ethanol to the fuel I use.

The only reason I state this is that the one trip I took to NJ this summer I averaged 27.6 MPG on the way home. The gas I purchased had no Ethanol in it.

Just my observation, but I am looking forward to seeing if anyone else has noticed something similar.

[hskrbob]

I am just wondering if anyone has religiously been using a lower grade than 93 octane in their IS250/350 and if they have noticed a difference in gas mileage/performance and or noticed any problems?

I have heard that you can use as low as 87 without any problems however I have also heard the opposite and the dealer states that the car might make some knocking noise's w/ lower octane.

It is understandable that you might get worse mileage with lower the octane but I was wondering if anyone has tried and had good enough gas mileage to make paying less worth it?

Everyone at the dealership said to go with the 87. I did a couple of tankfulls...never again. Premium does make a difference, no matter what the so-called experts say!

[Manolo1]

From the latest Winding Road edition:

""Most modern engines are fuel injected and controlled by sophisticated engine management systems which can rapidly and accurately compensate for lower octane fuel by retarding the ignition. Running these cars on 87 octane will not hurt them. However, the subsequent drop in fuel mileage and performance, not to mention the possibility of damage over time, may counteract the immediate savings at the pump""

Today the percentage difference between premium and regular is only 5% which is the typical loss in mileage most cars get by switching from premium to regular.

In summary it is a wash in the short term and a potential loss in the long term, plus reduced performance!

[Blayd]

Yea. I think if u use regular and just put som STP octane booster in it is cheaper but prob not as good quality.

[Gaugster]

Yea. I think if u use regular and just put som STP octane booster in it is cheaper but prob not as good quality.

Do what you like but the octane boosters are cool 'cause they make your plugs pretty colors.

[Blayd]

Hmm.. Looks like a bad thing to me.

[cdog818]

Hey friends..

I have a 2008, IS 250, and just completed my 5000 mile complimentary service at the dealership. There they changed my oil for the first time. My question is, now how often shall I change the oil? Shall I change it every 3000 miles like a normal car, or just wait until my 10,000 mile service. I know, I know...probably every 3,000 miles now. But still i want to know what you guys think?

Thanks..

[djspawn00]

you'll be fine with 5000 miles if you use an OEM filter and synthetic oil... but then again... you'll probably be fine for 5000 miles regardless...

[paradigm]

our car manuals state when you should change the oil and do any/all maintenance. dealerships tell you to change every 3k/3 months because they want $$$$ from you on a regular basis, not when your car actually needs the work done.