Porsche Macan Forums

I remember reading a review by Porsche years ago on high quality fuels v ordinary stuff. They reckoned there would be no difference in performance because the on-board computers would analyse the burn and adjust all settings as required. They firmly believed that there was no performance advantage to be gained.

I am not sure whether there was much difference in performance - but I found one car would run rougher when I filled up at some garages, so I stopped using supermarket and some local garages and used the local BP or Shell ones and it run far more consistently smoothly (I do recall having to fill up once from local Esso garage and it run badly until I filled up again).

I often wondered whether more than the additives whether there were other factors like condition of tanks, amount of turnover of garage's stock that were causing issues.

When I got a diesel (because of 20k commute) I continued until I moved and there was no sensibly located Shell or BP garage on route so started using supermarket stuff and tbh couldn't tell the difference.

Interesting. As the macan manual taylks about using 98 RON fuel, and not 95 RON if you can avoid it. So odd that they'd say the car will be happy with whatever fuel!

Either way, we're feeding our GTS with premium as its what we've put in all our cars! shell V power does seem to give the cars a little more oof, but could be nothing!

It's hard to tell just how much of this is our thoughts rather than actual real data? I remember watching 5th gear do a thing on premium fuel (petrol) and they concluded over five fuels they tried that a couple made a measurable, but unfeelable difference in performance - about a couple of percent - but it did not justify the cost.

I use whatever diesel I'm close to at the time after trying a back to back full tank premium diesel against the cheapest supermarket stuff I could find and I could not notice any difference at all - my car has certainly never ran "rough" as some people suggest?

James

For some reason best known to Esso, "synergie" is rated at 97 RON" but mine runs just fine on that from my local station

Off to France / Belgium (Spa) at the end of the month so not quite sure what I'll be able to find....it'll be interesting to see if I can feel any difference whatsoever, and if the mpg is noticeably different.

If they quote 97 then that is probably what it is. Esso tend to try to source their own production in the UK as much as possible (from Fawley) but exchange fuel where distribution costs can be reduced. They possibly supply 98 octane to the higher grade tanks then mix 98 with 95 (2/1) to get the advertised 97 octane.

I have only used BP ultimate and only at a petrol station that has high turnover.
That was advice I have read up and given by a few people to use high turnover petrol stations.

BP ultimate has been very smooth indeed in all my cars.

I remember reading a review by Porsche years ago on high quality fuels v ordinary stuff. They reckoned there would be no difference in performance because the on-board computers would analyse the burn and adjust all settings as required. They firmly believed that there was no performance advantage to be gained.

After all, it comes out of the same hole in the ground, it's just the additives that make the difference.

The engine management system will adjust to whatever fuel is supplied...but 98 gives higher output so should give better performance.

Have to correct the second statement: It does not come out of the same hole in the ground. Crude oil and gas is formed from dead sea creatures, underground and under intense pressure and temperature (coal is formed from dead plants). Crude oils that come from different parts of the world differ in both density and sulphur (and a host of other less important qualities). A quote:

"The variety of oils sometime seems as variable as the minds of man. Each source rock is unique and can vary geographically as well as geologically across it's extent. The kerogen (pre-oil) contained within these rocks have a chemistry determined by the origin of the organics originally buried millennia ago. A second influence is the chemical makeup of the rock.
One of the main differences is sweet and sour crude. Sour crude usually originates in a carbonate prone source which contributes the materials, usually sulphur, necessary for H2S or other compounds found in sour crude.
Another is the 'weight' of the hydrocarbon. It varies from a near pure methane gas to a bitumen thicker than the tar used to build roads. Much of this is caused by the orininal organic composition but further complicated by the heat and time acting on that material.
The higher prices go to lighter oils mostly found in the North Sea, Africa and the Gulf of Mexico. The Canadian oil sands are much thicker and therefore less valuable all the way around - higher production, transportation and refining costs."

If you then add into the mix the type of refinery used to process the crude oil (with/without reformers, cat-crackers, hydro-crackers, thermal crackers, isomers, with/without chemical plants etc) then the petrol produced can vary enormously...even within the constraints of high EU specifications.

Add to that the proprietary additives and you finally get the petrol you want...or not!

I have no idea whether the premium fuels improve performance or not but I do know that the manual says 98 RON is the preferred choice and having spent the amount I did on the car that's what I'm going to feed it.

BP ultimate is 97 RON. Tesco Momentum is 99 Ron. Perhaps refuelling alternatively with cooking then premium might be the best compromise. Assuming the need to save a few pennies.

I have no idea whether the premium fuels improve performance or not but I do know that the manual says 98 RON is the preferred choice and having spent the amount I did on the car that's what I'm going to feed it.

I also suspect the additives in premium fuels are likely to benefit the engine over the longer term so worth the few ppl extra

If the knock prevention is still by retarding the ignition a touch you'd expect the higher quality fuel to allow slightly more advance of the order of two degrees.
This tends to give a bit more power at high rpm.
I think the systems respond if the sensors detect more than one knock per 10,000 or so, YMMV obviously.