And engineered to run on stock tires and wheels, TGMO oil, TGMO filters and stock suspension. That doesn't mean we don't play with those parameters in a multitude of ways. And I didn't pay 70k dollars for my whip. I paid 30k. All I'm sayin is, if you want to save 20-30 dollars by running reg fuel, you can. Do I do it? No. BUT only because I get my fuel cheap and there's little difference in the price around my area.

 

The octane requirements of an engine are determined not only by its design and timing parameters, but also on the operating conditions and environments of the vehicle. For example, ambient temperature and altitude influence octane requirements.

For temperature, it seems that approximately every 7C +/- results in a change of +/- 1 octane. Which means if your car requires 91 in the summer, in the winter it would only require 87.

For altitude, it seems to be about a reduction of 3-4 octane per increase of ~1000m (or 10 kPa).

Spark advance/retard of 1 degree (360 degrees is a full engine revolution) results in a change of 1 octane.

So essentially, if you live at 3000 ft, or in cold climates, you could run a premium designed engine on regular, and the knock sensor would probably not even get triggered (assumed the engine was designed to run at sea level during temperate climates). How much closer to sea-level, or warmer, the climate you live in, spark timing would come into play.

So long as spark timing doesn't need to retard to prevent knocking, the engine should run just as well as it did on 91.

 

Detonation is bad. It puts stress on a variety of engine components. Yes, the knock sensor will pull timing... after it has already detected minor detonation.

If detonation happens occasionally, it probably won't create enough additional stress to cause a problem. You can run one tank of 87 if you find yourself in a place without premium or you accidentally choose the wrong grade. But if you run 87 all the time you will shorten engine life to some degree. If you don't plan to keep your car 300,000 miles maybe you don't care. But you are increasing the risk, by some small amount, of everything from head gasket failure to broken rods.

The car was designed around 91+; that is what will put the least stress on the engine and for that reason I run it.

(Head gasket failure is on my mind right now... I'm looking to buy a 2G Acura Legend and blown HGs are a major issue on those cars. The principal cause? Excessive detonation, caused by the ECU not being able to recognize a clogged EGR system.)

 

I agree. Here in socal the difference is only .20c a gallon at Costco. No brainer. I want the full HP rating and the full MPG rating. I can definitely afford the $4 more per fillup.

 

It is not just .20c difference it is 2 hours difference. I get stuck just trying to get out of parking lot forget about waiting in line.

Keep your engine running while in line and your MPG will suffer.
Turn your engine on and off and end up damaging engine more than filling up with regular.
I'd rather fill up with regular then waiting in line.

I am mentally challenged please explain me how some ones ability to afford to pay more per fill up or value of the car has anything to do with using regular vs. premium??

 

Thanks for "actual answers" to question posted!

 

Chuck - I see your point. But I can see the point on the other side too. I'm probably the cheapest **** on these forums. Why spend money that you don't need to? I do lots of things that others would not in order to save money. But I also have 7 vehicles and an atv. I have those because a) I want them, I'm a car / vehicle nut / idiot. I just can't help myself. And b) because I don't waste money ... at least on other things. I also have a mortgage at 2.875% and pound 20% into my 401k.

My post previous I didn't make clear, but I use premium BECAUSE I'M TOO CHEAP TO USE THE CHEAP STUFF. In my mind, I'm saving money by running premium because it *should* lead to less problems, expense and repair down the road in the long run. And I get the added benefit of a vehicle that performs the way it was intended because I'm running the correct fuel and maintain it to the letter. Lots of other guys do too. I would imagine most on these forums take exceptional care of their vehicle ... hence they are here to learn & find info.

My point is: I see your point, I don't mind such a question though. As I don't like to throw money out the window. I would run 87 too, but I think it will cost more in the long run. Just wanted to get my point out there. Maybe others will think my opinion has merit, and we can keep LS460's on the road longer, in better shape, and make 7 Series owners take notice.

I have two guys at work. One has a V-10 M5, the other has a 7 Series. The M5 has had about 3 problems over the last year. One was the SMG pump and was HIGH DOLLA. He has a warranty company. The 7 Series just had his transmission have a problem. Luckily had it repaired by a smart guy, only cost him about $900. The M5 driver is starting to consider selling the car because he is now worried every time he cranks it, if it's going to have a problem. The 7 Series guy just doesn't drive his car.

They both love my car and ask to ride to lunch in "the limo" when we go to lunch together. I digress. Anywho, love my LS and the foums!

 

The answer is YES you can run regular gas and it is your "limo" so feel free to run what you want. There are so many sensors on these cars that will "compensate" for the reg gas HOWEVER premium gas will make the car run better....... I am also a "car guy" and I have a Charger SRT that will run poor on reg gas so I always fill up with premium, I also have a UTV, JD Garden tractor, Honda generator and many other two cycle Sthil saws and weed walkers that I run high octane Avaition fuel plus a fuel stabilizer in them because of the associated Ethanol fuel problems so I am want my stuff to run at full potential and do not want any problems from the gas sitting...... If you can't find Avaition fuel buy some PURE FUEL at Home Cheapo.
I now know you are a "Thrifty Guy" (I don't like the word 'cheap') and have done very well for yourself so congrats on this BUT, Like I said before you should run premium gas because you car will run better and it was engineered for this....... Just read the tank cap!
You know the benefits of putting 20% into the 401k so think of running premium fuel along the same lines..... It will pay you back in the long run.
TIP! A clean, well maintained car, with premium fuel and oil is a Happy Car.

 

This is what I don't get. You paid a premium for this car. Even used, you paid more than you could have paid for a car, you could have bought a newer cheaper car, etc. Why would you not experience it performing the way it's supposed to in order to save a few dollars per tank of fuel?

It's like buying tires. You bought one of the best riding, quietest cars ever made. When you buy tires, are you going to buy off brand tires at the gas station or at WalMart or are you going to do some research and buy the best tires you can, even if they cost a little more in order to get the most you can out of the car you paid a premium for?

Something is not a better value if it costs less AND you get less.

 

 

Unless it is absolutely known throughout this controversial topic that regular unleaded will not register more knock trying to find itself every time you start your car because it thinks it's running the recommended octane I'm not using it. As Dal pointed out detonation is bad and you don't know you have it most of the time which will shorten the life of your motor. Why risk it until you know for sure.
Anytime there is food for thought and no clear consensus why would anyone risk it. I can understand if the difference was big enough to wager that risk but it isn't.

 

I notice that Lexus states that if using gasohol, that the octane rating be no lower than 87. That sort of implies that our engines can support lower octane fue:

 

Good analogy. I drove one used LS while I was looking for my car that had the cheapest possible Chinese tires. The car felt like crap, and sure enough when I looked around at other parts they showed obvious signs of maintenance on the cheap and deterioration. Why spend all the money for an LS if you're OK with that?

But at least cheap tires won't contribute to early mechanical failure, although they may get you into an accident.

 

Oldfart, you are sounding like an oldfart, lol.
You have to know when to go, obviously. In the morning or closer to closing there are no lines whatsoever.

 

THIS. it's a mindset difference.