Duh..... I did it this time. I usually drive a pickup that will just about run on anything, but this week when I stopped to fill up the XLR, I blindly filled it with low octane fuel. It only took one day for the wife to call me while driving it and ask if I had filled her precious with cheap gas. She knows her car and had figured out my mistake before I even knew what hit. The "pinging" was a give-away.

On the way home today, I picked up some Octane Booster and gave the XLR a dose in hopes of getting it happy again.

Has anyone had the "knocking" problem with mid-grade? Do you think the "Boost" will bring the XLR up in one tank full? My baby don't feel good; neither does my wife.

The Boost will hep - but keep topping off the tank with the premium as often as you can until the pinging is gone

Ken,
That's even worse than when I filled up my Impala with high octane by mistake....since I usually take the XLR in there for gas. Impala was happy, I sure wasn't.:nono :nono
Linda

Your motor should not "ping" because of low octane fuel.

The motor has a knock sensors on it "maybe two" and it will retard timing long before YOU hear it. THAT is IF it is working right..
This sensor has been on GM motors now for over 20 years.

I have been using ALL grades of fuel on my 2004 XLR and have only seen maybe a very small amount of difference in performance... This is with Methanol fuels..

NOW with Ethanol fuels you have to be careful.

TWO of the big things with Ethanol are:
It attracts water/condensation and shelf life is not very good.

If the fuel is over about 30 days old it may not burn very well and the store fuel tanks may have water in them. The stores should have water/fuel filter on each pump but they have to replace them a lot more if the sell Ethanol.

So only get fuel from a store that sells a lot of fuel and hope they change the filters a lot....

In the boats we service we are installing/servicing the water/fuel filter every four months if the customer uses his boat a lot.. We also tell the customer to add fuel stabilizer to his fuel if he can NOT use up his fuel in three weeks.....
We may have cleaner air/water but customers are have a lot more problems with there motors NOW because of old fuel....
Plus you may see a two MPG loss... BUT hey we have cleaner air/water...

If you are going to add "boost" to your fuel ONLY add what it says to add. NOT the whole bottle if it is not needed... The "boost" is mostly isopropyl alcohols and these eat anything rubber in the fuel system...


Hope this helps some.

Motorboat

Hopefully, the situation is already resolved, but the another option would be to run the fuel out of the car as quickly as possible (without diluting it). Gasolines are reformulated for seasonal changes so it might just have also been a one-time thing- or it might just have been bad gas.

I agree that the systems on the cars are sophisticated enough to catch most of the problems, but I've had minor, minor pinging on similar motors (you wouldn't notice it with the radio on) using regular. One thing that can help is to run some sort of fuel system cleaner through the car to eliminate carbon deposits that can exacerbate the issue. GM makes several good ones. Good luck.

I agree with motorboat. Knock sensors are not new tech, and if they are working there should be no pinging.

So, Ken .... how did this all turn out? :confused

Instant sucess. The wife hadn't used even an eigth of the tank and I added an LUCAS Octane Booster, best stuff made for the purpose. Within the next 25 miles, the XLR was purring and hasn't pinged a peep since. I think it even made the engine run better than before I made the mistake of filling it up with Reg.

BTW, we are now as 3.05/gal Reg; 3.15/gal mid-grade; and 3.25/gal premium.

Yea, I bet it was a mistake! With prices moving toward $4.00 a gallon out here in California, I think I'll make a mistake or two or three. Actually I do cheat once in a while. Every other tank is middle grade and I have no problems with my V.:thumbs
I may have to take out a loan to get a tank of gas.Instant sucess. The wife hadn't used even an eigth of the tank and I added an LUCAS Octane Booster, best stuff made for the purpose. Within the next 25 miles, the XLR was purring and hasn't pinged a peep since. I think it even made the engine run better than before I made the mistake of filling it up with Reg.

BTW, we are now as 3.05/gal Reg; 3.15/gal mid-grade; and 3.25/gal premium.

Duh..... I did it this time. I usually drive a pickup that will just about run on anything, but this week when I stopped to fill up the XLR, I blindly filled it with low octane fuel. It only took one day for the wife to call me while driving it and ask if I had filled her precious with cheap gas. She knows her car and had figured out my mistake before I even knew what hit. The "pinging" was a give-away.

On the way home today, I picked up some Octane Booster and gave the XLR a dose in hopes of getting it happy again.

Has anyone had the "knocking" problem with mid-grade? Do you think the "Boost" will bring the XLR up in one tank full? My baby don't feel good; neither does my wife.

My 04 runs fine on regular. I've never used high test or mid grade and never had pinging. May get a little better performance from high test but I think it would be negligable.

I don't believe my ears just heard that. You will also get better gas mileage with better gas, so your just trading apples for oranges and just might be voiding your warranty. Check your manual on what kind of gas you are expected to use in this vehcile. GeeeeeeeeeeezMy 04 runs fine on regular. I've never used high test or mid grade and never had pinging. May get a little better performance from high test but I think it would be negligable.

Bob,

Not sure, but I think my old XLR manual said regular is OK--not sure about that--I used to use mid-grade in the XLR. Course now it's nothing put premium.

Floyd

Well, I'm not sure either, but I'm sure someone here will have an opinion, so there.Bob,

Not sure, but I think my old XLR manual said regular is OK--not sure about that--I used to use mid-grade in the XLR. Course now it's nothing put premium.

Floyd

Well one things for sure when I put regular in my baby she really hesitates on take off compared to when I put super or mid-grade its a instant GO...I would have never thought the difference would be that HUGE!!!

Floyd,
I'm gonna go the other way on this one. I think it said premium. How about it XLR owners? Floyd and I have V's so we can't be sure. I do know at the meeting at the plant they said not to use anything but premium and didn't distinquish between the XLR and the V. They also said that damage would result from lower octane.
BoboBob,

Not sure, but I think my old XLR manual said regular is OK--not sure about that--I used to use mid-grade in the XLR. Course now it's nothing put premium.

Floyd

I have an 04 and the manual does say to use regular however after owning my XLR for about 3 months I noticed I couldn't accelerate like I thought it should. Asked my cadillac dealer and he said I should only use premium. Best advice I've had - no problems on acceleration.
Darrell

In my daily driving to and from work I sometimes use the midgrade with no noticeable difference. If I am traveling on the Interstete I use premium. It yields 10% better mileage (26-27 mpg) at a 3% cost premium. My XLR is a 2004 with 72,000 miles.

bumbleent.