I have an 04 XC90 T6 recently i had to get my entire engine overhauled because someone in my family had been using 83 octane which isnt ideal for this car becasue it is turbochargered and its a high end car. when the turbos kick in a higher compression ratio is gained and with 83 octane gas you get something called pre ignition which is the fuel is sparked is before the piston completes it's compression stroke. that put a nice crack in one of my cylinder heads call me crazy but the dealer said it had a little bit to do with the use of 83 octane. Ive noticed since i started using 93 the car runs much much better. one time i ran outta gas and i had a 8 gallon can in the car with 83 in it i put that in to get to a station and i swear the car didnt run as good as it did on 93. Now I know 93 is more expensive. But consider this you could either spent the extra 1.30$ per gallon and have a car that runs better with a cleaner engine. or you could save money put 83 into it and have it run worse. this problem not only caused 3 cracked cylinder heads im guessing the last 3 cyinders lucked out but it caused blown head gaskets as well. so just use the 93 your better off.

 

83 Octane? I didn't know they sold 83 in the US. I lived in Milford and New Haven for a long time but never saw octane that low. I've been running my XC90 T6 on 87 octane for 7 years / 105k miles with no problems.

 

83 Octane?

I´ve heard that something you should consider as european when importing cars from US to Europe is that the fuel in US is not of the same quality.

In Sweden it´s possible to get 95, 96, 98 or 99 octane at regular gas stations. For like 20 years ago we also had 93 octane but now 95 is the lowest...

What´s the highets octane level available in US?

 

They sell 100 octane fuel at the Sunoco down the street from my house.

 

sorry guys i feel like an idiot i typed this up originally on my blackberry i meant to say 87 87 octane was what was causing me my problems

 

Yeah, 87 can cause some problems in a turbocharged car, although I have been told not to worry too much with only half a tank or so with my other turbo car (BMW). If you were repeatedly running low octane, that is an expensive lesson.

The US and European octance levels are not equivalent (about 5 points), because of different calculations.

 

Isn't 87 all that's required by Volvo? I think I read it in the owners manual. If it requires higher then they should say so.

 

yeah they absoutely should. I always use to use 93 even in my non turbo cars I.E. 02 V8 explorer i guess the family tried saving a bit of money and used 87 for a few months when the money was tight and that caused our problems well now we know dont chince on gasoline since then i put 93 in everything i own, lawn gear, cars, pressure washer, generator if it runs on petrol it gets 93 which is hte highest level avialble in my state.

 

I am not convinced this is really an issue. I have never run any of my modern, fuel injected and computer controlled cars on anything but 87 octane. Not a single issue in over 1/2 million miles of driving vehicles 'requiring' premium gas? What your saying makes no sense to me and is not supported by the manufacturer. Unless you are racing the car or buying bad gas this cannot be a real issue.

Any chance you tried running diesel through your gas engine?

 

I don't know about Volvo, but most manufacturer's use a knock sensor (in modern motors) which sends a signal to retard the timing when pre-detonation is sensed. That being said if a manufacturer calls for a certain octane rating you should run at least that, especially in turbo motors with higher cylinder pressures. Detonation (pre-detonation) kills motors.

 

Volvos have knock sensors, tho on my 240 it never seemed to do anything.

From the '06 xc90 manual:

Minimum octane requirement - AKI 87 (RON 91) - unleaded fuel

 

Must be fairly low boost and low cylinder pressures then.