Fuel Octane rating vs mileage?

**Basil** · 10-29-2008, 06:29 PM

Just picked up my new 2009 XC70 at the dealership...and it was snowing :-) Think I'm gonna like this car :-)

I was surprised when the salesman told me during the delivery briefing to use regular (87 octane) unleaded. Not that I didn't believe him but I just checked the owners manual & that's exactly what it says! Has anyone been monitoring engine performance & fuel mileage using regular?... has anyone compared to when they are using super (91 octane)?

I guess I'll just go with reguar for the first few fill-ups and will report on my fuel mileage when I get the information.

If anyone has data, please share!

**jlf** · 10-29-2008, 06:59 PM

My wife and I just test drove the T6 today and our sales guy said the same thing. I would have thought the T6 would require super, so a little surprised. He also said our '04 x/c70 could use regular, and we've been using super since day one because the manual said it was designed for this....with 87 octane as minimum??

**beavenx5** · 10-29-2008, 09:24 PM

Originally Posted by Basil

Just picked up my new 2009 XC70 at the dealership...and it was snowing :-) Think I'm gonna like this car :-)

I was surprised when the salesman told me during the delivery briefing to use regular (87 octane) unleaded. Not that I didn't believe him but I just checked the owners manual & that's exactly what it says! Has anyone been monitoring engine performance & fuel mileage using regular?... has anyone compared to when they are using super (91 octane)?

I guess I'll just go with reguar for the first few fill-ups and will report on my fuel mileage when I get the information.

If anyone has data, please share!

Hi Basil,
We just picked up our 2009 XC70 T6 also this morning. Unfortunately there was no snow left on the ground this morning in the West Island to test the new car.
This would be great if I can use Reg gas in the T6. I have been running on 91 octane on both cars for a few years now

. The 2000 V70XC did not like the 87 octane and I totaled 2 catalitic converters after 6 months on my MB C240 because I was using 87 octane in it. I tought an 168HP V6 would be OK with 87 octane but the MB dealer told me that the use of Regular gasoline in my C240 was the cause of the failure (because of some aditives). I did not tell him I was using regular gasoline. So if Volvo says to use Premium, I guess it is better to do so.
I don't know about the new Volvo yet, but I could see a difference in fuel mileage if I use regular, even only once in the V70 and the C240.

**jlf** · 10-30-2008, 08:06 AM

What does the T6 manual say exactly for fuel requirements?

JF

**waldi** · 10-30-2008, 09:03 AM

Wow, I would be surprised if T6 would use regular gas. Usually turbocharged engine requires premium fuel to create pressure for turbo. I am picking my new T6 later on today and will ask that question for sure and verify with manual.

**dlmielke** · 10-31-2008, 08:08 AM

I'm just shy of one year driving the 2008 XC70 (with my '98 XC70 as the teen car). While I usually buy the mid-grade fuel, when prices were up around $4/gal I decided to check the manual. 87 octane is the minimum recommended, so I tried it. The car seems to run about the same and my mileage is not noticably changed. Maybe now that prices are down a bit I'll pump a tank of higher octane now and then.

**Lotus99** · 10-31-2008, 09:21 PM

From what the rep told me at pickup, so take that for what it's worth...

the T6 technically can accept 87 octane, but it needs 91 for maximum performance, and 91 is actually recommended. Oddly enough, the gas lid doesn't have a sticker on it indicating so, like most cars do.

**Lotus99** · 11-01-2008, 11:25 AM

Manual says: "Volvo recommends premium fuel for best performance, but using 87 octane or above will not affect engine reliability. Volvo engines are designed to achieve rated horsepower, torque, and fuel economy performance using premium 91 octane fuel."

So guess he was bang on.

**beavenx5** · 11-02-2008, 05:00 PM

Originally Posted by Lotus99

Manual says: "Volvo recommends premium fuel for best performance, but using 87 octane or above will not affect engine reliability. Volvo engines are designed to achieve rated horsepower, torque, and fuel economy performance using premium 91 octane fuel."

So guess he was bang on.

This is interesting... I guess Volvo must have sensors protecting the engine from knocking.
It would be interesting to compare fuel mileage using 87 - 89 and 91 octane fuel when our T6 engine will have enough mileage to run as per specs (after 5-6,000 KM I believe). I will do this in a couple of month when I go to the cottage... Always same road and driving conditions.

**HeadXC** · 01-17-2009, 05:21 PM

Used to run 94 in my 02 and 04 XC70's and the mileage was considerably better and was the performance. i was running 94 in my 08 until one day last summer i refused to pay 1.60 for it and put in regular, well that tank of gas gave me my best mileage yet (even though it still sucks compared to my 04) I still put in 94 once in a while cause of the results in the past models, but the same results over and over. I think regular will be the call after this and giving it some thought. Right now i;m getting 18 to 20 litres per 100 in the cold weather here. the worst my 04 ever got was 13-14 pulling a trailer in the winter.

They need to have a fix for this very poor mileage