what grade of gas are you filling up with ( 04 owners)

[Shoe]

Im curious what grade of gas you guys are putting in

shoe

[angelo]

Isn't the recommended grade regular for both 4 and 6 cyl?

[bigpow]

Lexus recommends premium grade ... I'm in denial and still think that I'd bought a Lexus ... Premium for my car then

[Buckeyegirl]

I have the V-6 and the service manager says it has 10.8:1 compression so I run premium. Can anyone confirm the compression ratio?

[Guest]

I have the V-6 and the service manager says it has 10.8:1 compression so I run premium. Can anyone confirm the compression ratio?

it says 10.8:1 on Toyota Canada's web site:
http://toyota.ca/cgi-bin/WebObjects/WWW ... 40e%2ehtml

[angelo]

I have the V-6 and the service manager says it has 10.8:1 compression so I run premium. Can anyone confirm the compression ratio?

it says 10.8:1 on Toyota Canada's web site:
http://toyota.ca/cgi-bin/WebObjects/WWW ... 40e%2ehtml

10.8:1 sounds like premium...
although at my dealership they told me that it can run on regular...

[samster]

I run regular. As long as it runs smooth and the mileage is good I will keep running it.

[rgache]

I remember reading in the manual of my 04 SE-sport that premium gas will enhance performance in the V-6 engine, but not the 4cyl. I have a new Sienna and the manual says the same thing.

Why would the 4 cyl. not benefit from the higher octane of premium like the v-6?

[fotodad]

I also noticed the manual said premium fuel will enhance performance. I thought any performance enhancement would be minimal. Wow! Was I wrong! I put a complete tank full of premium (91 octane) in a few days ago. Accelatation is dramatically better and, while I haven't run the numbers, it seems my mileage has improved as well. Now it's a matter of whether the extra money is worth the improvements. Plus I'm a little concerned about someone mentioning changing between regular and premium on a consisitant basis will do harm to the engine.

[rgache]

I also noticed the manual said premium fuel will enhance performance. I thought any performance enhancement would be minimal. Wow! Was I wrong! I put a complete tank full of premium (91 octane) in a few days ago. Accelatation is dramatically better and, while I haven't run the numbers, it seems my mileage has improved as well. Now it's a matter of whether the extra money is worth the improvements. Plus I'm a little concerned about someone mentioning changing between regular and premium on a consisitant basis will do harm to the engine.

Hey, if any of you technical moderators could chime in to fotodad's comments, it would be great. How about the 4cyl '04 models. Will they benefit also (see my prior post on what the new Solara manual says)?

[rgache]

Ok, I got curious on this issue and I e-mailed 4 questions on gas to my dealer from whom I just bought my 2004 SE-Sport; 4cyl, 5sp manual. The answers are from the service manager and sales person (very knowlegable on Toyotas) at Tuscaloosa Toyota. They are a great team and very responsive. Here are the questions and their responses.

Questions:

(1) Is there any danger in damaging the engine by switching between regular and premium grades? If so, why and what type of damage would it cause?

Response: No damage will occur to the engine in switching octanes. Sensors in the engine will determine if spark retardation is necessary due to pinging, but no other changes are made. No memory effect occurs in any hardware or software system in the Solara such that using one octane gas over another will cause latent faltering or not operate as specified in the manual. In other words, the engine has no systems that lock onto a particular grade of gas.

(2) Is there truly a boost in performance with higher octane gases?

Response: Yes, there is some, but the effect is probably negligable (i.e. 1-2 %). The 4 and 6 cyl engines rev so high that using a higher octane does not increase performance in today's engines. Older v-8 engines 20 years ago did experience noticable increases in power with higher octane gases. However, the 4 and 6cyl engines in the Solara burn gas so efficiently and rev so high that no gas is unused due to pre-ignition or other effects remedied by a higher octane gas. The 6cyl may experience some greater performance over the 4cyl (still 1-2%) because the RPM in the 6cly at a rated output is lower than the RPM of the 4cyl. at equal speed, however.

(3) Will mileage also increase? If so, does anyone know if the mileage increase will offset the $.20 increase cost per gallon for premium?

Response: Mileage will increase some due to the increase in power, but since it will only be 1-2%, the additional cost is not offset. Also, we note that from nominal high quality gas vendors (BP; Exon; etc.) premium gas does not have better detergents, nor is it better for your engine.

(4) Do both the 6cyl and 4cyl engines benefit from the higher octane? If only one benefits, why?

Reponse: Yes, both benefit from a performance standpoint, and the 6cyl might gain a little more, but you probably will not notice the difference. The Solara manual mentions the 6cyl gaining only because marketing brochures on the Solara rate the power output of the 6cyl using 93 Octane gas and Toyota does not want to get sued for false advertising.

Misc:

The sales person mentioned to me that they get a lot of placebo effect perceptions that 6 cyl engines get much greater performance from higher octane gases, but the data on actual performance does not support this perception.

[fotodad]

Russell,

Thanks for doing all that leg work! Your post answers all my questions! I appreciate it.

[slingshot]

Thanks for that very informative posting. I will now go back to using 87 octane gas instead of 93 and make sure it is always from quality brands. It's nice to hear confirmation that premium grade is a ripoff giving you at most 1-2% performance increase which to me is nothing.
Dave

[kamjah]

haha, i allways kind of assumed that those who said that their cars felt better on higher octane gas was just a placebo. ive been using regular every since i got my 04 se sport, and it runs perfectly fine.

as my v8 thunderbird friend says "anyone who uses anything but regular is a sucker" but then again, his v8 burns gas like a mother, lol

[fotodad]

I just filled my tank with regular. I'm ashamed to admit I fell into the premium-is-best trap. After putting in regular I cannot honestly notice a difference. Thanks for saving me some mulla.