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I wonder why GM did not go for a higher compression 3.6L that
would require 91 Octane fuel. Maybe then it power rating
would be 275HP/270ft-lbs.
 

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Hi,

The recommended gasoline octane according to the 2004 CTS owners manual is 91 octane or higher. It also says that you may use regular 87 octane with reduced performance.

I know that the compression ratio is higher than 10:1 but I cannot remember the exact number. I do know that the performance of this engine is great. My last auto was an Aurora with the Northstar 4.0 L DOHC 32 VALVE V8 and I must say that this engine definetly has better performance. On Sunday I decided to take a short drive with my wife, I enjoyed it so much that I just felt like going. When I arrived home I discovered that I had driven 187 miles. Take my word that this car can move. I was using the 93 octane at the time and I did not press the Sport mode button which is supposed to give you increased performance.

I have about 7 things written down that I cannot understand why Cadillac did not put in. Some were very simple like a glove compartment light that been in every car that I owned. Sorry that this is so long. Everyone have a great weekend.
Irwin
 

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Regular gas

If you call Cadillac, they will tell you that the first batch of 2004 owner's manual are incorrect. The recommedation for grade of gasoline was mistakenly carried over from the 2003 model year and the 3.2L engine. The 3.6L was designed to run on regular 87 octane fuel and only that. As I said you can call Cadillac, or you could read any one of a number of aut magazine reviews on this car, all of which say regular gas only.
 

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Thanks for the corrected information. I had been using 93 octane. Below is a copy of the letter that I just sent on the Cadillac Website.

Hi,
I own a 2004 CTS since September 17th. Last night I read a a post about the 2004 CTS Gasoline Octane rating on the Cadillacforums.com. It said that the recommended octane was 87. He wanted to know why GM didn't go to a higher compression on the 3.6 L engine so that 91 or higher octane could be used for better performance. I wrote back that page 5.4 in the 2004 CTS OWNERS MANUAL say’s to use premium with an OCTANE RATING OF 91 OR HIGHER. It says that 87 octane can be used with lower performance. I have been using the 93 octane.

He posted a reply to my post that said that the 2004 CTS OWNERS MANUAL IS totally WRONG and that only 87 octane should be used. There are many other things that are missing from this over $40,000 Cadillac.
I would rate my dealer Sarant Cadillac a 10 out of a 10. Its Cadillac that I am complaining about. I need a fast reply.

Thank you
Irwin M. Dresner
[email protected]

I will post the reply as soon as I receive as I receive it. There is no Excuse for an error like this. I was a manager of a high tech company and we always had several people double check what was written in the instruction manuals.

Have a great weekend everyone.

Irwin
 

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Re: Cadillac recommends 87 octgane regular gas

rgtc said:
Go to http://media.gm.com/division/2004_prodinfo/cadillac/pdf/04_Cadillac_CTS.pdf
This is a 2004 Cadillac CTS product information brochure. Go to page 6 where it gives engines specifications. You will see that Cadillac recommends 87 octane for the 3.6L and 91 octane for the 3.2L.

Thanks for the information. I just printed out the 8 page 2004 product information for the CTS.

I have also received a reply to the E-MAIL that I had sent to Cadillac asking about the recommended fuel for the 3.6L engine and they said 91 octane or higher as was posted in the owners manual. which they claim was correct.

I have just sent them another E-MAIL for clarification. I ask was the 91 or higher octane for the 3.6L engine with an automatic transmission.
I put down with automatic transmission because only the 3.6L one comes with the Automatic and there can no mistake about which engine its for.

You are certainly right according to the info in that product information book. Whats funny is that the 3.6L has a higher compression Ratio than the 3.2L why would the 3.2L use a higher octane?

Thanks again and I will post the reply. By the way I put 93 octane in when I drove about 200 miles about a week ago.

Have a great week everyone.

Irwin

I think that this Cadillac Forum is great
 

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Irwin,
The 3.6L was designed to run on regular 87 octane gasoline! If someone at Cadillac is telling you different, then ask to speak to their supervisor and keep going up the ladder until you get someone who knows what they are talking about. The fact that this engine runs on 87 octane is a big selling point of it and has been promoted as such by Cadillac throughout the major media sources. The people at the lower levels are just reading information that is front of them, whether it it right or wrong.
Instead of sending emails and not knowing who is responding to you, why don't you call Cadillac customer assistance at 800-458-8006. They have been very helpful to me. I have found that if they don't know the answer to a question, or if you disagree with their answer, they will investigate and get back to you.
 

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Re: Cadillac recommends 87 octgane regular gas

IRWINVET said:
You are certainly right according to the info in that product information book. Whats funny is that the 3.6L has a higher compression Ratio than the 3.2L why would the 3.2L use a higher octane?
Compression pressure in the cylinder is what matters, not static mechanical compression ratio.

Mechanical compression ratio more or less sets the maximum available cylinder pressure, but variable cam timing as used by the 3.6L engine allows the engine controls to manage this.
 

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I am a first time poster on this site.I enjoy all the exchange of info. I have a 2004 CTS 3.6 luxury and sport package .My first US car in over twenty years and I love it. My owners manual says 87 octane is ok but for best performance us 91 octane. talked to several auto techs and they agree. I ran some un scientfic tests on my own . with the traction control off trans in sport mode it will chirp the tires. and move out pretty good with 87 in the tank. With the tank full of 91 octane same conditions it will really smoke the tires.so there is definately a power increase with 91, but it runs fine on 87. I feel that with the lower octane, the computer retardes the ignition to prevent pinging.
 

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silver bullet said:
I am a first time poster on this site.I enjoy all the exchange of info. I have a 2004 CTS 3.6 luxury and sport package .My first US car in over twenty years and I love it. My owners manual says 87 octane is ok but for best performance us 91 octane. talked to several auto techs and they agree. I ran some un scientfic tests on my own . with the traction control off trans in sport mode it will chirp the tires. and move out pretty good with 87 in the tank. With the tank full of 91 octane same conditions it will really smoke the tires.so there is definately a power increase with 91, but it runs fine on 87. I feel that with the lower octane, the computer retardes the ignition to prevent pinging.
I believe you are right about the ignition timing and you will also find about a mile better per gallon with the 91.

I switched back and forth for a few tanks but now I run 91 only.
 

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Why not put 91 in the tank? I probably shouldn't be talking about this being i don't own a CTS yet, but if your gonna spend that kind of money on a car this beautiful, pay the higher priced gas. Why go cheap on something that your car depends on? I apologize if i offend anyone with this message. This is only my second post! :canttalk:
From,
SaM
 

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I completely agree with M STaR. If you have the resources to cruise around in a brand new Caddy, certainly money can't be so tight as to worry about gas prices. Personally, my car has never had anything added that wasn't 92 or higher. Most preferrably I seek out 94(Sunoco stations carry it as their Premium). I would never consider putting 87 <shiver> in my car(even if I was allowed to).
 

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This has been gone over SOOOO MANY times on SOOO MANY boards for different vehicles ive been on. In fact, BMW-Forums.com E46 board has the same discussion going right now. While the bimmer requires 91 or above, the general consensus is that if youre vehicle is not designed for, or does not require higher octane fuels, putting them in is just like throwing cash in the trash. Do not ask me to get scientific here as I can never remember the whole explanation, but essentially a vehicle designed for higher octane run on lower octane runs the risk of predetonation and other hazards, but a vehicle run on HIGHER octane than its designed for, does not gain an increase in performance (Edmunds editors put 100 octane Shell fuel in the tank of their test Ferrari 3xx car and surprisingly experienced no major increase whatsoever). It has already been stated that the manual for the 04 model is incorrect on recommendation of 91 octane fuel.
 

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Octane retards the ignition of gasoline. If you use higher octane fuel in a vehicle that does not require it you can decrease performance. Engines that run at high temperatures or high pressures require high octane gas to prevent pre-ignition. If you use a high octane gas in an engine that does not require it the fuel may not completely burn. Unburned fuel means greater pollution and the excess fuel can wash lubricant out of the cylinders (this is also the reason you should not let your car idle for long periods of time, ex. warming the car for more than a minute on a cold morning). Using higher octane fuel in a car that does not require it not only is a waste of money it can have detrimental effect on your vehicle.

The manual for my 2004 CTS 3.6 (December 2003 build) says to use only 87 octane in the 3.6. It says to use 91 in the 3.2 or the LS6, although you can use 87 in these engine as well (with possible decreased performance).

Fuel companies advertise that high octane gas is better, so they can get more of your money.

Modern engine computers can usually adapt to different fuel, but it is still best to use the suggested fuel.

I use 87 in my 3.6 and it performs great. I would not mind putting in 91 or 93 as it is a company car and my company pays for the fuel, but I will follow the manual.

Dan
 

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Ah, heck, just put in the 93 and SMOKE THE TIRES!!! (You get a new set free, if you have 17" on an '03 CTS by October 31, 2004)

SO, GO AHEAD... PLAY!!!:lildevil:

4WARD
 
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