fishbone

I've only been driving a used 04 TL for 2 weeks, and I filled the tank with regular gas for the 2nd time today. Then it occurred to me that I was supposed to fill it with premium grade. Does anyone know what effects/damage this has on the car? Should I use up the gas half way and mix the tank with premium gas or just wait until the tank empties?

eluzion

You're fine. Just don't go smashing around on 87 octane. The car is tuned for 91/92 and runs pretty high compression. Next time you get gas just fill it up with 91/92,

I hate cars

Drive it easy until you put the good stuff in. Besides not hurting the motor, you will see better mileage and more power with the good stuff.

Stew4HD

I have an '08 but I use regular most times. I don't push my car hard at all but she performs just fine. I don't believe that using regular will damage your car what-so-ever though we might not get the top performance that higher octane can bring.

bmaczo6

iTrader: (1)

The car will run fine with regular and it will not cause any damage. It will give up a little on peak performance but the vast majority of drivers will not notice a difference.

TypeSDragon

No damage, but at the end you will get higher mileage with premium, so you are not saving much.

csmeance

just a warning to posters, do not flame the OP, mistakes happen.

1995hoo

I've put in regular gas one time in four years (got my TL four years ago today). Last month I was in Louisbourg, Nova Scotia, running out of gas, and the only gas station anywhere in the area sold only regular. So I put in $10 worth of regular to hold me over until I was in a more populated area the next day. I didn't notice any knocking or decreased performance and the car ran fine, although I didn't really push it or anything (set the cruise control at 80 km/h for most of the way back up to Sydney) and I only drove about 50 km before filling up with premium.

People say you can run the TL on regular, but I was heading up the Cabot Trail and didn't want to go over the mountains in the Cape Breton Highlands on the cheap stuff.

The way I see it is that if you spend over $30,000 on a car, it's silly to cheap out on the gas unless you have no choice or unless you just make a mistake.

BuffBakerGA

iTrader: (2)

Using 87 octane will save you money but slightly decrease performance at WOT. It's a give and take. With 87, I actually improve gas mileage but it was from my driving habits, not the gas. It just happens that I drive slower with 87 vs the 93...

ChicoOG

I did notice a difference when I used regular, kind of made me nervous.

I currently get 24 mpg city/highway combined and drive approximately 24,000 a year, which equates to 1,000 gallons of gas. Premium is approx..30$ more than regular, which means I am paying $300 a year more for premium than regular, or $25 a month.

If you are only driving 12,000 a year, your looking at $12 a month.

I don't know what the mpg difference is between premium and regular, but assuming premium is better, that reduces the savings even further.

For some, $25 a month is huge, with sub prime mortgages, lay-offs, etc...

One other note, I just sea foamed my car after 84,000 miles. Even using premium and doing all the maintenance as scheduled, a LOT of gunk came out of the engine. I don't know how much worse it would have been if I would have only used regular.

Anyway, that's just my limited, non-technical, experience....I'm sticking with premium

SpecialFX

You should always use the proper octane fuel. If the car was intended to run on 87 they would say so. You may not see immediate effects of using lower octane fuel but long term it will affect your engine. The lower octane fuel in a high compression engine leads to detonation. The computer retards the ignition to compensate but can only do so much. Just because you don't hear knocking doesn't mean all is well inside the engine. Ever seen a piston damaged by detonation? It's not pretty.

Why pay for a higher performance automobile then cripple it by using cheap gas? You're not saving any money, as the car will get better mileage with the proper fuel, offsetting the cost difference. With premium running about 30 cents a gallon more what are we talking about, $3 per fill up? At about $4/gallon for regular thats about 7.5% more for premium. If you get 5-10% better mileage on premium vs. regular it's really a wash. Is that worth the potential of damaging your engine? It's false economy.

eluzion

+1

Use the proper octane level for your car. I can't imagine why any of you would fill up with 87 octane and try to go WOT either. Yes, cars have knock sensors and will retard timing when it detects knock but they are only effective at lower RPMs. At higher RPMs, they pretty much useless with all the engine noise. Here is an old post I made from on the Gixxer.com forums when there was a discussion about octane levels. Don't feel like retyping it:

Source: http://www.gixxer.com/forums/showthr...eluzion&page=3

"Actually, he was correct. Higher octane fuel takes longer to burn. But you are correct too (it does require more heat to ignite).

Again, the 600's will run fine on 87-92. However, the 600 was most likely tuned for 87 octane and that's what it really comes down to.

When tuning any internal combustion engine, the goal is to have the end of the combustion process occur at the "perfect" degree after TDC. People think the combustion process happens instantly, but actually it doesn't. The end of the process is what creates the most energy/heat, hence the reason you want it to occur at the right time. If it occurs to soon (say when the rod/piston is near TDC), you put a LOT of stress on the internals and usually leads to bent/snapped rods. If it occurs too late, you have wasted energy.

Ignition timing is the degree when the combustion process is started. On a car for example, you'll hear people say it's running "19 degrees of timing at 10 psi (turbo) at 8500 RPMs". 19 degrees before TDC the combustion process is started but it actually doesn't end until a certain degree after TDC (the "perfect" spot that has the most energy potential). It varies with every motor but I believe it's somewhere around 17 degrees after TDC. When you find that "perfect" spot, this is where your engine will create the most power (known as Maximum Brake Torque, MBT).

So what does this have to do with fuel octane? Why do you think you can run higher timing with higher octane? Because it burns slower. You can start the combustion process sooner. Of course you can't just add higher octane fuel and increase the timing since there is no secret/magic formula to show how much timing you need to add (dyno tuning is your friend). If the GSX-R 600 was tuned for 87, it will run best on 87. If you run anything higher, you're only wasting money and creating wasted energy.

Now, that's not the only thing octane does but a very important aspect of it on the tuning side of things. Higher octane can also be compressed much further before spontaneously igniting (this is why higher compression engines needs higher octane). Higher octane also takes more heat to ignite.

I personally run Chevron/Shell/76. Stay away from those cheaper stations (safeway, ARCO, etc.). As far as octane, I choose to use 89. I could probably get away with 87, but I don't feel very comfortable running that low of octane in such a high compression engine. In the tuning I've done on automobiles, anything higher than 11:0 C/R, we used 92 octane at a minimum. What I really want to do is find a engine management system for the GSX-R and re-tune it on 92 octane."

This is no different for automobiles. The TL recommends 91/92 octane and that is what it's tuned for. By using a lower octane fuel, the end of the combustion is occurring earlier which leads to increased cylinder pressure and wasted energy.

Another thing that is important to mention is higher octane fuels such as Chevron's 91/92 octane have higher levels of Techron which will help keep your injectors and combustion chamber clean.

Bottom line -- use the proper octane level for your car. Nothing higher, nothing lower. I laugh at people who put in octane booster or run race gas on their stock motors and believe they get more power out of it.

ndabunka

The above is utter nonsense. The TL (like MOST modern cars) can easily retard the timing to the point that there is NO DAMAGE what-so-ever. About 6 people on this thread already pointed this out. Your claims that the OP is (somehow) damaging his motor is like selling snake oil (you can't see it working but "take my word for it" says the con-man, it does)...

eluzion

Of course it can, at lower RPMs. I don't see any damage that could be done at low load / low RPM conditions but under high RPM or high load conditions, detonation is definitely a possibility that could damage your motor.

If you want to drive your car with your engine relying on a knock sensor to keep your timing at a level safe enough to run low octane then by all means go for it. If you want to drive your car with your engine running as it was intended to, as in the ignition values it was tuned for at the proper octane level which will give you the best overall performance and level of safety, then run what the manufacturer recommends.

JnC

iTrader: (12)

Meh, I am not here to change any one's belief but I have always used 87 in my current 06, older 02 and 00 TLs without any problems. My brother has the 00 that I use to own as a DD and he has 250k miles on the odo and returns about 29 MPG (75% highway) driving. My 02 TL-S was fine with 87 as well and when I sold the car it had 155k miles on the Odo and it use to do 25/32 mpgs. The current 06 is fine with 87 as well returning 28 mpgs (75% highway driving).
I remember RnT or C&D did a test a few years ago where they dyno'd cars such as honda Accord, Sti and E46 M3 to see what sort of a difference lower and higher octane gas makes on BHP. Accord seemed to do just fine with both gases where as Sti and M3 lost some bhp due to the octane difference.

The following Fifth gear test only concurred to my belief that putting higher octane gas in a NA car such as TL is useless.

http://www.youtube.com/watch?v=0QGCYLwTCGI

Timeless

How I hate these threads....

Run premium!

CarrieLynn

iTrader: (2)

Your check engine light may come on and you will feel a loss of power.

I always use premium gas but had to use regular once...and that is what happend to me. I took my car to the dealership because of the light, I didn't realize that was why it was on. I guess the the o2 sensor knew I had put regular in and that is why the light was on, as soon as I put the premium back in it never came on again.

1995hoo

This thread started out well enough given the OP's query where he had put in regular by mistake, but now it's turned into the usual sniping about "I use regular," "You're a fool for using regular," "How dare you suggest that; you're an idiot for spending extra money on premium." Given all the threads on that aspect of this topic over the years, I think it's time for one of the moderators to do this....

eluzion

No one is calling anyone a fool. The point of a forum is for discussion, and a discussion we are having!

SpecialFX

OK, smart guy. So you know more than the engineers who designed your motor? Good luck. Of course modern electronics can compensate partially for the increased volatility of lower octane fuel. But only within certain boundaries. Even if you can't hear any knock that doesn't mean all is well. If an engine could run safely on regular why would the designers specify higher octane? They make no money from the sale of premium vs regular. And the fact that the computer has to retard the timing to compensate - does that not tell you that it's not optimum for the engine?

I don't care what you put in your gas tank. The OP asked for a factual answer, not opinion. This has been discussed here before in great detail. Anyone who is interested can search this site and also many other sites to get facts. It's not as if the motor will blow up immediately when it senses 87 vs 93, but the long term effects are bad for the motor. And the reduced mileage that results from the use of lower octane fuel negates any savings you may see at fill-up. Why bother?

ggesq

iTrader: (1)

fishbone- welcome to the forums. I believe the answer to your question has been provided. At this point, I am closing this thread as it has shifted gears into a discussion that has been rehashed over and over and over again.