Octane Sensor?

BloodyVolvoDriver · Post by **BloodyVolvoDriver** » 12 Nov 2011, 17:47

Just wondering if my MY 97 S70 2.5 20V has a octane sensor? I have been putting the highest grade of fuel, and recently come to a realisation that it does very little difference in mpg compare to lower octane fuel e.g. 91RON. is it just money gone down the drain then? Should I stop filling up with good fuel if it makes little difference??

Post by **rspi** » 12 Nov 2011, 18:41

I alway fill up with 93 octane. Your car along with most newer cars are tuned as high compression motors. The run better on 92+ octane. They will run on lower octane but it really isn't good for the motor. It could be the difference between the motor lasting 200,000 and 500,000 miles. These cars do have knock sensors that allow them to run fine on lower octane (the law requires our cars to be capable to run on 87 octane). I usually get 15% better mileage with 93. There are things you can do to get a little better mileage, you may want to read up on some suggestions. There is a good rightup on getting better mileage on VF. http://volvoforums.com/forum/general-vo ... ove-52933/

Post by **tjts1** » 12 Nov 2011, 19:41

BloodyVolvoDriver wrote:Just wondering if my MY 97 S70 2.5 20V has a octane sensor? I have been putting the highest grade of fuel, and recently come to a realisation that it does very little difference in mpg compare to lower octane fuel e.g. 91RON. is it just money gone down the drain then? Should I stop filling up with good fuel if it makes little difference??

If you don't have a turbo its a waste of money. The car doesn't have an octane sensor, it just detects knock under heavy load. Low octane fuel will be more prone to knock under high load and high temperature. If you drive like a normal person you'll never notice the difference.

Post by **jimmy57** » 12 Nov 2011, 19:53

+1 on tjts1's comment.
If you are driving easy to maximize fuel economy then you are not loading the engine enough for it to need the higher octane. IF you have to drive in mountains, especially at ambient temps over 30C then go to at least mid-grade.

The fuel detergent levels, at least in North America, are more than adequate in all grades and have been for 10 years. I bet Ford, Holden, and all the others put the same pressures on fuel sellers down under to get their detergent levels adequate so the car makers didn't have issues with fuel systems.

bigkev414 · Post by **bigkev414** » 13 Nov 2011, 02:00

BloodyVolvoDriver wrote:Just wondering if my MY 97 S70 2.5 20V has a octane sensor? I have been putting the highest grade of fuel, and recently come to a realisation that it does very little difference in mpg compare to lower octane fuel e.g. 91RON. is it just money gone down the drain then? Should I stop filling up with good fuel if it makes little difference??

They told me that unless I used 98 in the S70T sport i recently bought it would cause the engine electronic management system to bring up a fault light. I did, and it did too.....bring up the light I mean. Took it to Volvo and they reset it and said it was detecting something awry with the fuel mixture. Went away, filled up with Caltex 98 ron and the light came on again. Car went perfectly. Luckily I know the Volvo service manager because I've had 20 of them over the years and they reset it, and he said it was because it was 'woolworths' Caltex and do not use it. Also stick with 98. Also advised (privately) to put some injector cleaner in and go for a thrash along the highway to clear the cobwebs out. Did that, and the light came on again.
The owners manual says to use 95 for my model and I will. To hell with the light - I'll ignore it.
I've had so many 'dud' batches of petrol over the years it's not funny, but the Volvos usually don't like Shell in my experience. By the time I buy 98 and pay the full price without a discount docket I can't afford to drive the thing - it EATS fuel!
Have a look in your owners manual at your engine specs and use the RON rating it recommends. I'm going to cover the light over and go to the local Mumbai (7 eleven) station and fill up there on the cheap days.

BloodyVolvoDriver · Post by **BloodyVolvoDriver** » 13 Nov 2011, 03:51

Rightio, thanks. What about fuel with ethanol? Is it going to lots more corrosion inside the engine?

Post by **jblackburn** » 13 Nov 2011, 08:04

My (turbo) hates 87 octane but runs just fine on 89. The only time I can tell a difference between 89 and 93 is on very hot summer days with the AC running.

Just about every fuel you get on the East Coast here has 10-15% ethanol.

Billc1015 · Post by **Billc1015** » 13 Nov 2011, 08:43

I have a 94 T-5 and it runs just fine on 87. Sure I don't have the power that I get with 92-93 octane but the engine runs fine. I just don't beat on it. When I go into full boost to pass someone or get on the highway there is a difference but I'm okay with it. Now I am running completely stock so it can handle it. If you have tuned your ECM or did other mods for higher power then you would definitely want to run high octane at all times.

bigkev414 · Post by **bigkev414** » 19 Nov 2011, 06:23

Put Shell 95 in the S70 and she went like a dream. Yesterday, Caltex Woolworths was cheap so I put 25 ltrs of 95 in and the engine management fault light came on again, but the cars goes OK. Unlike all the other Volvos I have owned this one seemed to like the Shell best. My 740's and 240s' hated Shell. Who knows what we are getting.

BloodyVolvoDriver · Post by **BloodyVolvoDriver** » 20 Nov 2011, 06:34

bigkev414 wrote:Put Shell 95 in the S70 and she went like a dream. Yesterday, Caltex Woolworths was cheap so I put 25 ltrs of 95 in and the engine management fault light came on again, but the cars goes OK. Unlike all the other Volvos I have owned this one seemed to like the Shell best. My 740's and 240s' hated Shell. Who knows what we are getting.

My S70 absolutely HATES Caltex for some reason. I filled mine up with Shell 95 the other day and got 65km/10l

It's not like I drive like a hooligan or anything though. Shell and BP is the best