Premium vs BP Ultimate

[mickofoz]

Sorry if this has been covered before. I have always used BP Ultimate on all my cars. Recently though, due to the high fuel prices, I opted for Premium for the first time. To my surprise the car, Tiguan 125 TSI, actually used about 0.7L less on average. I filled up with Premium again to make sure this wasn't a fluke and again, the end result was about about 0.7L less.
Has anyone else tried this?

[team_v]

So to clarify, you usually use 98Ron but decided to use 95 due to the cheaper cost at the pump and noticed better fuel economy figures?

From my experience 98 gives a better fuel economy figure and is better for your engine.
I wouldn't chance 95 just to save $4-5 at the pump

[NZTiguan]

Sorry BUT it was a fluke, if you did a double blind test in identical conditions you'd get the reverse result.

[mickofoz]

I have filled up with Premium for the 4th time today and I'm still getting better fuel economy, some fluke.
In regards to Premium being a "bad" fuel for your car... that's your opinion. I only keep my cars for 3 years so it doesn't make any difference to me.

[kaanage]

I wouldn't chance 95 just to save $4-5 at the pump

The ECU should detune the car if it detects pinging from the lower octane level - this should really only happen when the engine is stressed with WOT as any throttling will lower the effective compression ratio.

Perhaps the 95 RON fuel has a higher energy density than the 98?

[team_v]

I don't think there is a specified timeframe for when damage will begin to occur if you use lower quality fuels.
Still so long as you are happy using 95 then go for it.

Also as Kaanage pointed out the ecu can de-tune the care so it is not as powerful as you aren't using the higher quality fuel.

Just be aware that you are the exception rather than the rule for fuel economy using 95.

[mickofoz]

Well thank you for your input. Like I said, I'm just stating facts, my observations. Whether it fits in with what we believe should happen is not the issue here. You should not damage your engine with 95RON fuels as it is the recommended grade by VW.
I will keep using Premium to see if it changes over time. Like I said, I will get a new Tigga next year so I will not be left stranded by a blown engine when all I was using is the VW recommended grade of fuel.

[Prodigy]

I've told the wife to only put 98RON in her Tiguan as thats what i've always used in all my turbo cars, however as mickofoz states, on the fuelcap i'm pretty sure it says 95RON as a minimum by VW so i can't see why there would be any issues if you do use it.

[Tig-uan]

What I noticed on my Tig 125TSI manual, the average consumption improves by 0.8-1.0 L where I use Shell V-Power 98. Prior to that I was using mostly Ampol/Caltex 98 Optimax.

I am sure this is not a one-off fluke as I alternated between Shell and the others several times, and the improvement happens everytime.

I would not dare try 95.

[Diesel_vert]

What fuel you can or should use depends exactly on what the sticker in your fuel flap says:


1. "Unleaded petrol 98/95 RON" = Use 98. You may use 95, but with reduced performance.

2. "Unleaded petrol 95/91 RON" = Use 95. You may use 91, but with reduced performance.

3. "Unleaded petrol min. 98 RON" = Use 98. You may use 95 only in emergencies.

4. "Unleaded petrol min. 95 RON" = Use 95. You may use 91 only in emergencies.


Please note, at no point will using unleaded 95 RON result in engine damage (except for no. 3).

[Sharkie]

Well thank you for your input. Like I said, I'm just stating facts, my observations. Whether it fits in with what we believe should happen is not the issue here. You should not damage your engine with 95RON fuels as it is the recommended grade by VW.
I will keep using Premium to see if it changes over time. Like I said, I will get a new Tigga next year so I will not be left stranded by a blown engine when all I was using is the VW recommended grade of fuel.

95 RON is not the recommended fuel ..... it is the minimum allowed. 98 RON is the recommended fuel. I have an email from VWA wherein they state that they consider Premium to be 98 and not 95 and that they recommend using 98 at all times.

[MGV]

Interesting topic... I have a few mates that will only run BP Ultimate in their bikes. 2nd choice is the Caltex 98 fuel, & they say they will only use Shell if nothing else is available, quote 'in extreme emergencies'... Don't know where they get their info from, but they do know a lot more about engines than i do, hence my choice for BP Ultimate in both the Buell & the VW...

[GTi Bhoy]

Correct me if im wrong and this may be getting of topic, but arent BP the only fuel company who guarantee there fuel will not damage your engine ?
Only on Ultimate though.

[Diesel_vert]

Correct me if im wrong and this may be getting of topic, but arent BP the only fuel company who guarantee there fuel will not damage your engine ?
Only on Ultimate though.

No, BP and Shell guarantee all grades of petrol, diesel and LPG.

Don't know about Caltex or Mobil - they may (or may not) have a similar policy, but I can't find any details on their websites.

[jcubed]

Fuel Grades at Altitude

All very interesting, but where we are, purely academic.

"Where" being at an altitude of 1600 to 1700m asl.

When the switch-over occurred locally from leaded to unleaded fuel, the only octane level available here, was 93. This was only recently upgraded - and also only by some petrol companies - to an option of 95. So the BP Ultimate locally, is actually 95 octane.

98 octane is only available at the coast, and say, 300km inland. This makes sense, as up here you can run Avgas (130 octane rating) if you like, it won't help one little bit due to the lack of air to burn it with - on a normally aspirated car, that is.

VW did not at any time issue a warning that you must add an aftermarket octane booster to your fuel when only 93 was available.

Subaru did though. In fact, the first Imprezas were detuned until 95 became available. If you wanted to run your standard STi, you needed to add racing fuel to each tank at the pump. Came in a bright yellow tin.

So, I doubt you would cause ANY damage if running a lower octane rating fuel. All modern engines have knock sensors, so the timing will be retarded with poorer fuel. You'll just loose some performance.

What would explain mickofoz's experience, is that he can "feel" - a rare gift, but some of us have it - that his car has less power from the lower octane fuel, and subconsciously adapts his driving style to it, hence using less fuel.