Hey guys,

Figured that would get your attention. Ive just read on here where someone said that the 240 is meant to run on 91+ octane.

I run 87 octane and have been getting 22-25mpg with 99% highway miles.
This is pretty good but i got the idea that could help us all squeeze a little bit more out of our cars.

I think we could all benifit from learning if 91+ octane has any benefit. Even if it is more$ it might offer enough gain in economy to make it worth it.

OK so here is the calling. I am planning on gathering data from you guys and myself and looking into this idea.

Here is what i need: (i need data from each octane level so even some good 87 octane data is needed)

Year:
Model:
Wagon/Sedan:
Turboy/n)
Fuel octane used:
gallons burned:
Miles driven:
MPG (calculated from above):
Type of conditionshighway/stop and go/city)
Average speed:
Load: # passanger, "stuff" weight in lbs (estimate)


I will be using this data also for one of my classes in school.
I will only use complete sets of data.

I hope you guys can help me out and supply some good data.


STeve

 

correct me if I'm wrong,
But i believe they are meant to run on 91 RON or (research octane rating)

the pumps in the US, (or at least all I've seen) use the average of the RON Rating and the Motor octane rating. (RON+MON)/2

And an Octane rating of 87 using the average formula ='s 91 Octane in the RON formula.

 

Hi sofobvolvo0909,

Thanks for posting about this topic. I recently commented in a previous post here at volvoforums.com that:

"The engine will run on 87-89 octane, however it is designed for 91 or better. It has a 9.8 to 1 compression ratio. You'll feel, hear, notice the difference in performance and fuel economy. Particularly the low end torque. I run Shell 93 year round and it loves it."

Might depend on the model year, miles on engine, driving habits, mods, etc. My car does better with 91 (RON+MON)/2. U.S. I started using it back in Sept. when I read in my owner's manual that 91 was recommended. I will read it over again to be sure. I may be mistaken.

For my Car.
Year: 1990
Model: 240 DL
Wagon/Sedan: wagon
Turboy/n) n
Fuel octane used: Shell 93
gallons burned: 12
Miles driven: 250
MPG (calculated from above): 20.8
Type of conditionshighway/stop and go/city) city/very short trips
Average speed: 45
Load: # passanger, "stuff" weight in lbs (estimate) 1 driver - 150 lbs / spare tire & stuff, tools - 100 lbs

Note: I get 22-23 average when mixing several interstate trips with city driving per 12 gallons. Avg speed on interstate 60. Tank holds @ 15 gallons. I don't let it get too low. The best mpg I ever got was 26 round trip from Nashville to Knoxville. This was a month ago. I have since changed the oil and rear diff fluid and replaced some tune up parts and engine mounts/transmission mount.
I hope to get some new tires on it soon and try the Nash to Knox round trip again to see what mpg's come out. Around city driving too.
Don't know if the stations around here in Tennessee have changed over to 'winter blend' yet. That might skew the test results?

Final note: My car has the 280 000 951 ECU computer. It didn't come from the factory that way. I think it must have been replaced at some time with the previous owner. Supposed to be a better version according to many posts on various forums. Whatever...

Also, I learned that 87 - 89 octane contains more heat potential energy than 91 - up octane. It allows the engine to warm up faster. Compared to a high compression engine running 91 - up, which needs less heat in the cylinders to prevent knock. Hence, high octane's rep for preventing knock.

To wit, my 99 ford expedition doesn't like 91. Runs great on 87. Ford told me that many newer vehicles (late 90's up) are more sensitive to the octane of fuel. A higher octane in an engine made for say, 87, will make apparent any deficiencies in the tune up of that engine. Call it tolerance, if you will.

This will be very interesting to watch. Hope you get many participants.

-Brandon

 

Wish I could help but I have to run my car on a mix of half 94 from sunoco and roughly 108 race gas from VP or it pings, le sigh. But only in the "winter, during the summer i put the timing back and run just 94.

 

Heres my info from my last fill up.
(I'm **** enough to track all my fill ups)
This is without an overdrive also.

Year: 92
Model: 240
Wagon/Sedan: Sedan
Turbo: (y/n) No
Fuel octane used: No name supermarket 87 octane
gallons burned: 10.930
Miles driven: 254.6
MPG (calculated from above): 23.294
Type of conditions: (highway/stop and go/city) Highway=90% Stop and go=10%
Average speed:62 highway 45 stop and go
Load: passanger = 240Lbs, "stuff" = 20Lbs (estimate)

 

My *guess* is the slightly higher MPG you'll see with the higher octane in a 240 won't be enough to justify the added cost. I personally try to keep up on maintence items since that seems to have the greatest effect on MPG.

An unfinished project of mine is to connect an LED inside the car to the "buffered" output of the O2 sensor so I can watch the lean/rich cycle.

 

Thanks Hotcrown. Your not the only **** one here i hope. (me included). Can someone explain the ((RON+MON)/2) equation and what RON and MON are?

Thanks

 

This is an interesting thread. I will try and get some numbers. I have tested both 87 and 93 and 93 is definitely better for hill climbing. I have tested this one hill on the way back form work many times and the lowest I get to with 93 is 63 mph, and with 87, just about 55.

 

• Year: 1975.
• Model: 245.
• Wagon/Sedan: It's a 245 so wagon.
• Turbo: Nope.
• Fuel octane used: 91, what else can I put in a 10.5:1 engine with no knock sensor.
• Gallons burned: 18.
• Miles driven: 455.
• MPG: 25.
• Driving conditions: Half and half.
• Average speed: 70 on the highway, 20 in the city.
• Load: 200 pounds of me, but very little extra crap.

It's worth noting that I have a different engine than you guys. I got a the venerable B20 engine, only used for one year. I don't have an overdrive though, not available on the manual in the first year.

 

1985 740GO
1990 745GA
1992 940GA
1994 945GA
1995 940TGA
All use 87, and they ALL love it, or else they go hungry! Waste of $ higher octane in a Volvo IF they don't ping which a healthy Volvo never does.

 

Any turbo Volvo should run the highest octane fuel you can find. Earlier turbo engines can and will detonate on hot days if you don't run it, later turbo cars will pull a whole lot of ignition timing once they detect knock.
I run 98 octane in my modified 740 Turbo wagon. It gets 10.5 litres/ 100 km everywhere, stop go traffic, highway, doesn't matter!

Regards, Andrew.

 

Im new to Volvo, but Ive put nothing but BP 93 octane in my Land Rovers. When I purchased my first one (97' DI), it was having some engine issues. I was never one to believe that using high octane fuels made any differences. That quickly changed after I became a member of LandRoversOnly, and was informed by many that the Rover engines are not only designed to run on 91 or higher, without it, the engine will actually start having issues. I was told to slowly wien my Rover off the 87 to 91. I did so, ran seafoam thru the motor and oil and the increase in MPG and performance was very noticable. Ive been running 93 thru everything I own since. Ive had my 240 Wagon for a few weeks now, and Im already noticing a smoother running engine. Even If the MPG dont increase by much, Id think running a fuel that is going to burn cleaner would be worth the small increase in price. Really.... Its not that much.

 

I used to own a Rover P6 with the 10.5 compression engine. It would ping on even teh highest octane fuel I could buy! Those Rover donks are nice though, would make a great Volvo swap.........

Regards, Andrew.

 

I've been putting 89 in my 93 wagon, but have been considering moving up. It's starting to get cold here-- does anyone have any thoughts on the higher octane vs. lower in cold weather? i am clueless there.