I've got a 1995 850 non-turbo wagon. The manual says it needs 91 octane but I have a feeling that only the turbo versions really do. Can I put in 87 with no difference in performance and durability?

On page 130 of this month's Road & Track the octane issue is discussed with regard to a 1995 Porsche 993.

It is worth reading

"Now, under favorable conditions - average temperatures and light duty driving - you can likely get away with 87 octane. But if the temperature rises or you put your foot down, 87 may not be enough to avoid pinging. this could lead to engine damage over the long haul."

The article also discusses the economics of lower octane. At 15 mpg and a 40 cent difference in price, you would save about $266.80 over 10,000 miles. I think that the figure will be much less than that as the cited milage is low and the difference in price is high IMHO. For me, I spend an extra buck a week.

The very next Technical Correspondance letter discusses injector cleaners and says

"Major oil companies say their regular gasolines have enough detergent added at the refinery to stop deposit formation. Premium gasolines have even MORE detergent, so they can cleanse away deposits that have already been formed" (emphasis added by me)

Make mine premium.
--
2 8s & 2 7s 600,000 miles total

Just to add my $0.02,

The car will run just fine on 87, and will probably develop enough horsepower to satisfy you. But it will not get the rated 167 hp unless you permit the timing to advance (without knocking, of course), and this requires 91-93 octane.

So for those occasions when you really want to accelerate onto the freeway from a stop, or pass somebody by accelerating from 45 to 65 quickly, the 167 hp comes in handy.

Gerald C

The car will run on 87, 89, 91 (93 and 94 as well). Volvo suggests 91 or better for better performance. In an 850 you will not feel knocking or pinging in the car with a lower grade gas, as the computer compensates for it. The 87 will work fine, use 91 or better for faster acceleration, cleaner burning, probably better mileage (although it's a catch 22 with the price of premium!), etc.

Brandon
95 854T 90k
95 944 114k

I've got a '95 850 Wagon that has been drinking 87 octane since we bought her new. She's got 175,000 miles and we've never experienced any knocking or pinging on 87. Occasionally I'll put a tank of 89 or more in, but didn't really notice a lot of difference in performance.

Ken

It really says a minimum of AKI 87. I have a 1996 NA - 855O. I will typically run midgrade 89 and get a little better mileage and not have to pay the premium of premium. With an occaisional tank of 91 I do get slightly better mileage and the computer seems not to want to retard the spark as much, so there is a little better performance.

Your choice - none will really harm durability - I do however have my doubts about the "cleaners" in pump fuel being very effective so I run Amsoil PI through every so often.
--
http://www.fidalgo.net/~brook4/oilslubesfilters.html

I ran 87 for several tanks. I averaged 21.1 mpg city. I changed to 91 and after 3 tanks, I am averaging 23.9... Pulled one of the O2 sensors, it was quite clean after the 91, although I didn't pull and check it after the 87 tanks... It pays me to run the 91, evenat $1.43.9 / gal here in Denver...My car is a turbo, and I get "into" it occasionally.

My experience is that octane value does make a difference. With 89 octane gas,
my acceleration characteristics were poor, and my fuel economy was 16 mpg in the city.

With 93 octane, I get about 20 in the city. This is with a '96 854 GLT (non-turbo)

Ashok

You are asking 2 questions;
1. Can I put in something other than 91 octane?
2. How will it affect my car?

The answer to #1 is YES you can. Any car sold in the US can run on 87 octane gas without damaging the engine. (you can live on twinkies and hamburgers too)It's the answer to #2, effects on performance, that makes the decision as to whether you will or not.

To run on a lower octane than the car was designed for, the engine computer has to change some of the fuel delivery and ignition timing parameters. This usually means that the car will lose some performance and usually some mileage too. How Much? That depends on the car and the driver.

What I did to test my car was the following:
First I ran the tank nearly dry. Then I put in 1/4 tank of premium and then run it nearly dry to allow the car's computer to adjust to the gas. I kept a notebook and wrote down the mileage on the odometer when I next went in to fill the tank with premium. I ran 2 consecutive tanks of premium gas to nearly empty, noting the date, mileage on the odometer, the number of gallons of gas every time I filled up and any other comments about performance. Then I ran 1/4 tank of 89 octane to reset the computer to the new gas and repeated the test but with 2 tanks of 89 octane. You can repeat it with 87 octane too if you want.

After determining MPG for each grade of gas, take the cost of the 2 tanks and divide it by the number of miles you traveled on the 2 tanks. This gives you cost per mile for gas.

For my car I got better mileage with the premium gas. Enough so that it was actually slightly cheaper to run the premium even though it cost more to buy.

Do the test and let us know what you get.
--
Nathan Valles, Black 855R, MBC, tint, strut brace, RE 730's

Probably not. Mix 93 and 89 alternately to maintain 91 octane.
--
(98 S70 T5SE misc mods, mostly lighting) (92 940GLE)

I have a 96 850 Turbo with 89,000 that I purchased in January of this year. We have had to make many repairs to the vehicle, but I love the car. Recently we had to replace the knock sensor...$650.00 later we have the car back. Lower octane gas can and will effect the knock sensor and it isn't a cheap fix.

Even in turbo models, there is no requirement to maintain 91 octane; the
requirement is 87.

If it makes that big a difference in your car, that is an indication that your
engine has become the victim of an upward creeping octane requirement which
comes with combustion chamber deposits but not necessarily with age (I use
DurAlt fuel additive to keep my engine's octane requirement to a minumum).

So this is where we get into the YMMV area...

And do remember, nothing beats a trial like a failure.

- Dave; '95 854T, 127K mi