Volvo 850 - gas type?

Do all Volvo 850s require premium gas?

As gas prices have risen plenty in the last year - I do not want to
purchase a vehicle that requires premium.

From the 850s on - which require stricltly premium?

My old 240 and 740 did not.

(Side note - the 740 GLE is the BEST car in the world - yes, I know
some of you are raising your eyebrows).

Thanks,

Tmuld.

 

None do. They may perform better and get better gas mileage with
premium, but they have a knock detector that will adjust the timing to
the grade of the gas. I have had a '93 and '95 850 and a '01 V70XC and
never used premium in any of them. No problems. I like to run a tank
of Chevron with Techron every once in a while, or get a can of Techron
and add it myself, but never had any problems.

 

My '95 850 manual says: "Volvo engines are designed for optimum
performance on premium with octane AKI 91 or above (AKI = RON +
MON/2). Minimum octane requirement is AKI 87."

This implies that although 87 is OK, the higher (premium 91 or above)
would be 'better', yes? Any harm done in alternating tankfuls, or
should I just stick with one rating?

Jay

 

It's about efficiency. The knock sensor will adjust the timing OK, but
it is compromising an engine that was designed to be able to use
premium, so it will necessarily make the engine less efficient - less
power and less mpg.

Depending upon the price difference between the grades of fuel, you
may actually find it cheaper to run on the more expensive stuff. There
wouldn't be any point in alternating tankfuls.
--

Stewart Hargrave


For email, replace 'SpamOnlyToHere' with my name

 

There

Actually, if one didn't let the tank go dry between fill-ups, alternating
tankfuls would raise the average octane level, since there would be at least
some 91 octane in there with the 87.

I don't know if I would waste the effort. 20 cents more for premium times 15
gallons is $3 per tankful difference if it's completely empty. I would spend
the extra for increases performance.
KennyH

Horsepower is cheaper than therapy.

 

....or lower it.

--

Stewart Hargrave


For email, replace 'SpamOnlyToHere' with my name

 

You've made a direct hit, I think--and the logic of your argument is
even more persuasive here in Europe.

Not sure what you're paying but not long ago we heard the shock! horror!
stories of 'two bucks a gallon for gas!' in America so let's use that
price for the purpose of illustration. If regular is $2.00 and premium
is '20 cents more', then your '$3 per tankful difference' represents a
10% increase.

In Finland (where I am), today, a typical price for regular is 1.159
euros per litre and for premium it's 1.189 euros per litre. That
translates (at today's exchange rate) to US$ 5.35 and 5.49 respectively,
per US gallon. The price differential here is only 2.6% more for
premium.

Assuming your 15 gallon ( = 57 litre) fill, that's $80 for regular and
$82 for premium. Does it make any sense to scrimp for a lousy two bucks
per tank, on a bill of 80 bucks?!? My '95 850T is happier on premium,
and when my Volvo is happy, I'm happy. (Of course, I'm one of
those guys who changes oil every 3000 miles, too.)

One last point: you say '15 gallons...if it's completely empty'. The
tank capacity on my '95 is 73 litres, which is more like 19.3 gallons.
Maybe the US models were different?

cheers,

Henry

 

Your manual says it all. No harm will be done if you stay at or above
87. There is no point in alternating. What would make a more sense
would be when you fill up to use part one octane and part the other IF
you saw a difference. Gas stations don't have a rule that says you can
only use one grade. You can mix grades at the pump. You will have to
pay twice at a "pay at the pump" station, but who cares if that is what
you want.

Your manual just says you will get better power and, perhaps, better
economy from 91 octane or better. The experts, "Click & Clack," say to
use the grade that gets the best miles per $ for you. Any better grade
is just a waste of money.

My '65 Austin Healey Sprite would get 30 mpg on regular and 35 mpg on
premium. It turned out I got the same miles per $ no matter which grade
I used. I haven't notice that effect with my Volvo 850s.

 

Has anyone ever done a test - see the mileage difference on a base 850
with 87 then with 91?

There is a difference of abotu 20 cents/litre of gas here. I think
one US gallon is 3.8 litres. The difference is substantial - but if
mileage was equitable - it might be worth it.

Anyone try this or have info on where I can find this info?

Thanks,

Tmuld.

 

Thanks Stephen, It makes sense to me.
Jay

 

You're all forgetting the altitude factor as well. At 5280ft our pumps all
offer lower octane levels.

 

Can't say on an 850, but my '95 Passat VR6, over 100 miles of
comparable driving was only about 2 MPG better....not enough from an
economy standpoint.

Ron/Champ 6

1963 8E5 Champ (Champ 6)
1962 Lark Daytona Convertible (Boomerang)
1995 VW Passat (Vanilla..yuk)
1994 Volvo 850 (Tilley)

 

Uh, I left a '0' off...1000 miles!

Ron/Champ 6

1963 8E5 Champ (Champ 6)
1962 Lark Daytona Convertible (Boomerang)
1995 VW Passat (Vanilla..yuk)
1994 Volvo 850 (Tilley)

 

There's an exception. Turbo engines, like my 850's, have their maximum
boost limited by the output of the knock sensors.
So, higher octane = less knock = higher boost = more power.


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Spammers are VERMIN. Please kill them all.

 

If your mixing and matching 87 and 91 then why not put a whole tank of 89
octane in?? We always used to run our 740 on 89 octane, with premium 91 when
it was time for a long trip (didn't make a difference for just around
town).... We have 87,89, and 91 at almost every filling station around here,
maybe you don't have the three grades everywhere where you live?

 

Think out of the box. Try mixing 87 and 89 if 87 doesn't work as well
as 89. If that is not a problem, then stick with 87.

 

Conversely,
lower octane = more knock correction = lower boost = more economy.

 

I have with both my '93 and '95 with highway driving and saw at most a
one mpg difference between 87 and 91 octane. Definitely not significant.

 

In terms of pure economy, it all depends upon the price difference
between the grades of fuel. A turbo is not about simply chucking more
fuel into the engine.

The more boost (or compression) you are able to employ, the more
efficiently the fuel will burn, which means extracting more usable
(kinetic) energy out of the same amount of fuel. This is a fundamental
principle of engine design.

The limiting factor is the ability of the fuel to withstand the
initial combustion pressures without detonating spontaneously before
the flame front reaches it. This is what we usually hear as knock,
although there can be other causes for it, too. An engine will be
designed to use a fuel that will not detonate at a given maximum
pressure. This is governed by compression ratio and turbo
overpressure. If lower octane fuel is used there is a danger of knock,
and in order to prevent this, the ignition point is retarded so that
P[max] occures later in the descent of the piston and will
consequently be lower. This will result in relative inefficiency.

An engine that needs to retard its ignition timing to prevent knock is
not using the ideal fuel to exploit its combustion pressure fully, and
cannot be working at optimum efficiency.

Most drivers tend to use the extra energy that a turbo releases as HP
rather than torque (many turboed cars are set up to maximise this),
which may mitigate against achieving greater mpg. One problem with
turbochargers is that they don't start working well until they are
spinning fast, so at lower speeds, running less boost, a turboed car
(which often tend to have lower compression ratios) will be naturally
inefficient.


--

Stewart Hargrave


For email, replace 'SpamOnlyToHere' with my name

 

And in the real world a turbo'd gasoline engine will almost always get worse
fuel economy than the same engine without a turbo. Both of mine get several
mpg lower than the N/A Volvos in the family even driven conservatively.
Worst economy is on regular, mid grade gets the best mileage, and premium
allows a bit more power for around the same mileage as regular, I usually
run mid grade. The 240 has no knock sensor and pings on regular at 14 psi so
this mostly applies to the 740.