I have driven my '05 V8 on a regular gas and got 13.2 mpg (as computer says) after 2 tanks -city driving only. Decided to go w/ Premium 93 octane- computer says 12.9 mpg after 1 tank. The trip computer seems to be quite accurate and gives very similar number to what I got by dividing mileage by the # of gallons. With V8 I did not notice major difference in acceleration bet. regular and premium gas.

Manual says the engine is designed for optimum performance on octane 91 or above, but 87 can still be used.

I am doing to try 1-2 more tanks on premium, will post results -may take a weeek or two.

 

In a V8, I would use premium.

 

Interestingly I had a similar finding in my c-70. For 'normal' driving I could not distinguish any performance difference although I know there would be a difference in 'spirited' driving.
R

 

Reg is correct. And maybe a slight difference in gas mileage as well. It is better on the engine in the long run.

 

Could you get into more details - they (Volvo) say regular can be used, my wife drives for short distances almost whole day, so we spent a lot on gas- if I can save some money, what is the reason not to?

 

The reason not to is to make sure everything is done to avoid future possible engine problems. I'm sure that the grade of petrol used will not have a profound effect upon the car but taking the risk is up to you. If Volvo says regular can be used, I'm sure you can trust them.

 

"If Volvo says regular can be used, I'm sure you can trust them."

they also say that the oil should be changed every 7500 miles -using a regular mon-synthetic oil. SO I do not trust them completely. As someone already said, volvo needs to make sure the car makes it to 48000 miles w/o major problems, after that every problem is more money to the dealer...

 

So why are you second guessing yourself? That is hypocritical. I advised you to use 89 or 91 but you insisted that you wanted to save money and Volvo assured you that regular was fine.

 

Interestingly, I was sitting in a physician's office today and picked up the 2005 automobile issue of Consumers Report. Understand this was...........I believe a March issue (remember we are in a physician's office) and all the Volvo models called for "regular/premium" fuel indicating that you could use either. I had a Millenia and an Audi that both 'recommended' premium but the handbooks made it perfectly clear that the autos would run very well on regular but that the performance would not be up to par. I ran them on regular.
R.

 

These magazines! Only instigating confusion. Well, I do not think there will be severe problems as a result of running the car on regular. It's just not as good as using premium. The way I calculated it was, if on average (currently in LA), 91 is $3.10/gal and 89 is $3.00/gal and 87 is $2.90/gal. My car needs to have it's 18-gal tank filled every 2 weeks (this varies on the distance driven). Thus, 26 weeks/52 in a year, I need to fill up.

91 - 26 x $3.10 = $80.60
89 - 26 x $3.00 = $78.00
87 - 26 x $2.90 = $75.40

Therefore, I will only save a total of $5.20 annually!

 

Fire2 I have to correct you. You will save $93.60 over one year. Using premium in an 18 gallon tank will set you back $55.80. In 26 weeks you will have paid $1,450.80. Using the inexpensive stuff you will be paying $52.20 per fill up or a total of $1,357.20 per annum. The difference between the two is $93.20. Your point is well taken, though. Really not much of a difference but then again, the principal of the whole thing!
R.

 

Oh yes! Reg, you're absolutely correct. How silly of me, I forgot to multiply by the # of gallons! Well, the fact is that even though the annual difference is $93, it is a worthy investment.

 

Well, Fire2 - I would not mind to pay $50 or so extra a year, but the focus of my observation was that it looks like the V8 gets BETTER MPG on a Regular gas. Acording to my calculator w/ you CA prices(same here in NY), if I put 20 Gal bi-weekly, the difference is about $100.00. Not much. The manual states: volvo engines are designed to perform best when gas w/ AKI of 91 or above is used, however the minimum octane rating is 87. Why do I get better mpg on a regular?! I bet even Volvo does not know the answer.

PS
MPG is down to 11.8 so far on 93 octane gas, was 13.2mpg on 87 octane....

 

Yurionel, that was my finding also. Recall that I have a 5 cylinder high pressure turbo. I do believe that the performance factor would probably be compromised but be that as it may, I still find the performance to be A-1 and I do not 'drag race' a Volvo.
R.

 

volvo engines are designed to perform best when gas w/ AKI of 91 or above is used

That basically answers your question. If you're concerned with mileage per gallon, use regular, but if you are concerned with the engine's performance and longevity, go with 91.

 

There seem to be no difference in performance w/ V8 engine, longevity is a whole different story - no one knows how durable yamaha's V8 is. As far as I understand if no knocking happens when going uphill on 87 octane- the engine is fine.

 

Then filling up with 87 shouldn't be a problem.