What type of fuel are you using?

[geokilla]

Put good in, get good out.

Not true. I remember my dad tried filling our old Civic with premium gas. Couple days later, car was sluggish and gave CEL. Filled it back up with regular and everything was back to normal. Just saying

[jblackburn]

The reccomended gas is what you SHOULD always use in your car. There's no point putting Premium in a car that's not designed for it.

My dad used to run Premium in his Saab (the base 8V engine, not a turbo), and killed his cat. converter with it after about 10 years. I put Premium in our 2007 Honda Accord once, and there was absolutely no difference. I can tell a definite increase in the power of my Volvo, and the smoothness of my old 1988 Accord when I used Premium. Regular shouldn't hurt an NA engine as it can adjust pretty readily without a whole lot of finagling, but I would never run it in a turbo engine. As soon as that compression builds up, the gas can detonate and cause a burned valve before the computer has a chance to adjust, especially with a heavy load on the engine and hot outside temperatures.

[vladvo]

I am just curious as to what fuel most people are using in their 850's, are you using regular or premium? I think the manual for my 1995 850 says to run high octane premium fuel but for the 1 year that I have had my car I always just put regular.

I was running reg. for awhile when I first got my '96 850 na (oct '09)....then in Jan. I switched to prem....It seems to be quite a bit happier with it.(doing some mileage checks now) I was getting 23.5 on reg.average around town and some short trips....I'll keep you posted on what's going on with premium

after a few tanks of premium,I made it up to 27.1 mpg with all around driving....got an oil change coming up soon ,also plugs an air cleaner....I'll keep you posted .......running real good at this point !!

[polskamafia mjl]

Glad you are happy.

[vegasjetta]

So I did the seafoam, then an oil change. I will report back what kinda mileage I am getting as well. I run 89 octane all the time now...

When I did the seafoam, the smoke that came out was bad enough to render the street undriveable for at least 10 minutes:

[polskamafia mjl]

Holy crap. +1 for running 89. How is she doing now?

[Hoov]

Well, this is an interesting thread for sure! I love these threads because we all get to find out what really works.

Having been involved with racing cars & motorcycles, owning an airplane & 1 full blown fuel drag boat I have dealt with the “which fuel issue”. Or in the case of the boat “How do we mix it today?”

My understanding of the octane rating is it measures the fuels ability to remain stable when subjected to heat & pressure.
More heat = higher octane requirement.
More pressure = higher octane requirement.

On a 1996, 850, GLT (n/a) there is no reason to use anything more than 87 (US).
That said, I am assuming the fuel is of good quality to begin with.
Additives in fuel are a big deal & some of the cheaper fueling stations buy whatever is left over so the fuel they sell can vary in quality from week to week. LOL (Good luck proving that though other than personal experience)
Over the years I have fussed & gommed with this issue & my personal findings have been I have never realized any advantage using a higher octane rated fuel than what the manufacturer recommended.

Obviously Turbo owners have different needs. Yeah, the car will run on 87 but given the stresses likely to be induced, would see much better results with higher octane. I might even stretch that thought by saying somebody that likes to stand on the throttle stop light to stop light, in a N/A, might also see better results. … Or at least not burn valves. … … as quickly.

What puzzles me is a few have reported better gas mileage.
Doesn’t make sense to me if the regular they were using was of good quality to begin with & they were running a n/a engine.

Arizona in July? Yes! CA … Even in higher elevations? Can’t see it. … I’m only talking about N/A engines with good quality fuel.

What am I missing? Higher octane fuel is not “zippier” it’s more stable.

Hoov

[polskamafia mjl]

I don't know if you have looked over the manual or not but Volvo recommends 91 or 93 even for the NA engines. The better gas mileage is probably a result of the timing not being retarded to compensate for the lower octane gas. There really is no way to prove which fuel is better but I refuse to use 87 on my NA.

[850tech]

Premium is just gas that contains a mixture of hydrocarbons that is slightly less combustible than the mixture found in lower octane gas. I know saying regular is more combustible then higher octane fuels sounds counter intuitive, but if you understand the principals behind Detonation this all makes sense.

Detonation, also know as Pinging or Spark Knock, occurs when combustion has already been correctly initiated by the spark plug and the fuel mixture is starting to burn through the camber, but then one or more pockets of air/fuel mixture ignite outside the envelope of the normal combustion front. The resulting shock wave collision creates the metallic pinging sound and cylinder pressure is increased.

The effects of engine knock can range from completely inconsequential, to catastrophic destruction of internal components.
An example of worst case scenario would be detonation induced Pre-Ignition (Pressure and heat ignite fuel before spark plug fires), which occurs when combustion chamber components get too hot due to prolonged periods of mild detonation and most often results in melted and burnt pistons and valves. This is why we have a turbo control valve and knock sensors

In conclusion, Octane stabilizes fuel and any mileage or performance gain is due to the elimination of combustion imperfection resulting in an optimized burn process. Understanding this, they will run on 87, and in many cases run fine, but for my peace of mind and my love of boost, its 91+

edit: Turbo engines are more susceptible to detonation due to the excess pressure and heat, in case your wondering.

[Hoov]

Premium is just gas that contains a mixture of hydrocarbons that is slightly less combustible than the mixture found in lower octane gas. I know saying regular is more combustible then higher octane fuels sounds counter intuitive, but if you understand the principals behind Detonation this all makes sense.
edit: Turbo engines are more susceptible to detonation due to the excess pressure and heat, in case your wondering.

BINGO!!!

Marcin, you state you own an "854". Is this different from an 850? My manual states "87" ... If It's wrong I will gladly change my thoughts. I am with all the rest of us! let's just get it right! ... I know you are in the same place.