[6girl]

Guys, I have just finished my third city tank of fuel since I bought the 6 - I decided on my last refuel to put Shell Optimax in the car to see if it would improve fuel economy. I am very happy with the results - 500km from 50 litres i.e. 10L/100km. My best using ULP was 12L/100km so it actually worked out cheaper to use Optimax.

The only down side was a loss of power - according to my arse-o-meter, not anything scientific like a dyno I knew that I wouldn't get a power gain (the 6 doesn't have a knock sensor and it was designed for ULP) but I wasn't sure about a loss of power. Oh well, it does kinda make sense - less power, better fuel economy.

I now have Caltex PULP (it's called Vortex) in the tank - I have already noticed it has more power than when using Optimax, but it also has a lower RON, so that would explain it. It will be interesting to see what fuel economy I get.

[Edited by 6girl on 05-10-2001 at 08:26 PM]

 

[Nathstx5]

The higher RON # the more explosive it is, therefore making a bigger explosion = more power!

 

[VooDoo]

I think i started a thread about Optimax & Mobil Synergy a while back and I found I developed power gain from Optimax also greater fuel economy.

I also found that Mobil Synergy 8000 (Optimax equivalent) I got power loss and sh!tter fuel economy.

Ive tried Vortex havent noticed much of a difference between it and Optimax, but then again I havent been running it long enough...

Im sticking with Optimax as my choice of fuel for power gain and economy.

Anyone else got feedback on these fuels???

 

[6girl]

Hmm

I would have to disagree with you there Nathstx5.

I subscribe to http://www.autospeed.com.au (which is a fantastic website) and they published a report from US fuel giant Chevron corp called "Petrol and Driving Performance"

Here's a quote:

"Knock-free engine performance is as important as good driveability. Octane number is a measure of a petrol's antiknock performance - its ability to resist knocking as it burns in the combustion chamber.

It is difficult for a driver to know whether a petrol has the antiknock performance the engine requires when the engine is equipped with a knock sensor system. These systems, which temporarily retard spark timing to eliminate knocking, are installed on many late-model engines. Retarding the spark reduces power and acceleration. The knock sensor responds so quickly that the driver never notices the knock. Loss of power and acceleration will be the only clues that the antiknock quality of the petrol does not meet the vehicle's octane requirement.

Using petrol with an antiknock rating higher than that required to prevent knock or to prevent spark retardation by the knock sensor will not improve a vehicle's performance."

Bottom line - and I have had this confirmed by Mazda directly - unless the car is designed for PULP you will not get a performance gain and the MX6 is not designed for PULP.

I know some people feel as though they are gaining power - I don't know how to explain this as the cold hard facts seem to indicate otherwise... I may have imagined a power loss as well..

 

[VooDoo]

6Girl how the hell did you get 500km on a 50 litre tank?? Im curious


Ive been driving Optimax for months now and I can only get an average of 430-450km per 58 Litres with optimax

And an average of 380-400km per 58 Litres with regular shell unleaded.

It aint my vehicle because Ive spoken to a few MX6 owners and they say the same?

 

[6girl]

Oh dear, now comes the embarassing part....cough, cough...I, um, actually ran out of fuel on the way to the petrol station..(blush, blush).

I have never run out of fuel before...have never owned a car with a fuel light before...for some reason the fuel light didn't come on till just before I ran out of fuel...even though the gauge was on E I ignored it because the fuel light had only just started to flash on and off depending on the angle of the road....

I was going down a steepish down hill and I lost all steering control and my dash lit up like an Xmas tree - it was actually very scary because I was on a main suburb road and I didn't have the strength the turn the car into a side street. I didn't realise I had run out of fuel - I was thinking 4WS failure or something really drastic like that.

I realise this all sounds pretty stupid, but in my defence I have only filled up the tank on this car 3 times and had never used Optimax, so i wasn't sure how many kays I should expect. Also on the first city tank I filled up almost the moment the fuel light first flashed on - and it only took 40 litres (380 kms) so the second tank I drove it only the fuel light for days and filled it up with 48 litres.

I shall now be using the gauge as a guide and fill up when it hits E.....(she says, feeling very sheepish)

 

[6girl]

One more thing..

SideFX - how do you use 58 litres when we only have a 58 litre tank? I can testify that there are several litres which are unusable... nto try to be pedantic, I'm just a little confused..

 

[VooDoo]

Accordig to the owners man the vehicles Fuel Light lights up when you are on your last 10Litres

So on a 58 Litre tank after using 48 Litres your light will come on....

I usually fill when it lights up and get about 46 Litres into it.

Not wise to let the tank go completely dry, something Mazda has made sure I knew saying all the Impurities and gung that settles in the fuel tank get pulled into the fuel line causing injector clogging. I was told to fill on the warning light :?

You can run the tank completely dry by the way, it is possible!!

[Edited by SideFX on 05-10-2001 at 09:37 PM]

 

[6girl]

That's all fine if your fuel light is working, mine isn't and I have learnt that the hard way

 

[Losiho]

I'll just add my 2 cents worth....

I only use Optimax. I can't say that I feel any performance difference, but it just seems to be a "cleaner" running fuel, and my engine seems to run better using it.
I get about 9 - 10.5L/100Km in the city. My worst in 13.2L/100Km, in January in peak hour traffic with the a/c on full. The fuel light is annoying, you always have about 10 - 15L of fuel in the tank when the light starts flashing.

BTW 6girl, if you are sure that you did not see your fuel warning light come on before you ran dry, then I would get your fuel sendor checked out.

 

[6girl]

Losiho - I totally agree with about the car running smoother on Optimax - I could notice it straight away. I'm getting sick of people telling me that using PULP in our cars is a waste of money - the guy from Mazda I spoke to was almost rude about it.

If it runs smoother (higher octane reduces combustion volatility) and seems to run more economically then I think if we are prepared to pay the extra money then what's the problem.

Well that's my spit for the day.

 

[Losiho]

6girl - That's a different attitude to my dealer, he said that it was a good idea to use PULP and advised me to keep using it....right after he gave me a bill for $120 for an inline injection clean !

 

[trevorg]

Hi all,

1) The MX-6 does have a knock sensor. It will vary the ignition timing by upto 14deg. That is why when you start it first thing in the morning it goes like the clappers for the first 5 minutes. We actually lose 10hp once the engine warms ups due to the knock sensor winding back the timing as the engine warms up. You also feel it more on really hot days.

2) I have used always used Premium or Optimax for the last 20 months. I dropped back to regular unleaded in January to see if there was any difference. My ass-o-meter register a significant lose of torque between 1500 and 3000 rpm. Above 3000 didn't feel different. Trip meter registered 60km less for the tank.

3) RON, In Australia we use RON Register Octane Number, in the US they use the same name RON but it is actually the average of RON and MON (Motor Octane Number)that is why in the US threads about this they refer to lower numbers ie
AUS RON 98 + US MON 86 / 2 = US RON 92

Trev

 

[Guest]

Thanks for clearing that up Trevor (the knock sensor); this thread had me running for the manual. Knew the Probe had a knock sensor & couldn't believe Mazda would dud MX6ers.
My experience is similar to (or its was when it was my everyday car) PULP = smoother running, better performance, better km per tank (BTW 550km per 50ltr around Sydney in the Probe is typical)

 

[4WSboy]

6Girl how the hell did you get 500km on a 50 litre tank?? Im curious


Ive been driving Optimax for months now and I can only get an average of 430-450km per 58 Litres with optimax

And an average of 380-400km per 58 Litres with regular shell unleaded.

It aint my vehicle because Ive spoken to a few MX6 owners and they say the same?

I'm averaging 10L/100 around town.