Am I wrong using supermarket regular unleaded in my new 991 or should I be using super unleaded, and if so, why?

You have spent 80k+ on a 911 and want to use Aldi fuel? Its nuts.

Use Shell V-Power only. Its 98 octane and will optimise your cars power/efficiency. There could be circa 20-30bhp difference.

Would you put bisto gravy on an aged fillet steak?

MTR

97?? The VPower down my way says 99 Octane on it - shirley it's the same everywhere?

V-Power is fine, as is Momentum. Haven't tried the BP stuff in some time (Ultimate?) but my previous car didn't like it.

As far as I understand it Porsches will run on unleaded but it's not recommended.

Yes, but they make the difference.

Just finishing my shift at a fuel Terminal.

For our engines to detect a higher octane fuel then use V Power when possible as it is the only fuel that is refined and delivered UK wide by the Company that is selling it (Shell)

Momentum 2nd as it is 99 octane.

As far as our handbooks say fuel needs to be 98 octane to adjust the ignition so using BP Ultimate or other "super" products will not have the desired effect.

Fuel is shared amongst the big players, supermarket fuel is exactly the same quality as the other "premium" brands. In fact it mostly comes out of the same tank.....

Bed time!

Your 991 will detect lower octane rated fuel via its "knock sensors" and retard the ignition to prevent or lessen pre-ignition. Result, slightly less power than the engine has been designed to produce.

It won't harm your engine/car and once an octane rating similar to that recommended (98 for a 997?) is used, the system will advance the ignition accordingly. However, a common misconception is that higher octane rated fuel simply produces more power, which it does in an engine optimised to utilise its anti knock properties. As its calorific value is the same as lower octane fuel, there are no performance gains to be had from an engine not optimised to use it, like an old stter such as a Rover 400.

Locally I can only get 97 RON fuel, but can't detect any difference to the odd time I have used 99 RON (saw a 100 RON pump in Germany last year).

What octane is the SUPER fuel at Sainsburys?

I always try to use Shell V-Power but since they sold out their local garages to BP, it has meant my closest is now a 30 mile round trip to a motorway service station which is even more expensive! Plus all the Shell garages I've been to of late have been incredibly battered and old and even getting fuel into the car was a challange; at one station it was clicking off every second (even upside down etc) that I gave up at £8 and told the cashier that didn't give a t0ss!

I find BP also to be fine...but when I go to my local tesco which is an esso petrol pump, I notice a difference (for the worse), BP and Shell premiums are best for me and Tesco 99 isn't too bad...(in a 996/7 turbo)

Do you not get carbon build up on the 95 RON stuff? Or is that an urban myth?

I use excellium (from Total) as they are the garages near me, then it's v-power.

On a road trip last to Italy i used a 100 RON fuel from Tam Oil. Everything just felt 'better' (I know you can't quantify a feeling but..). i even thought the engine note sounded a bit fuller (again probably bullst).

Esso fuel to me makes the engine on my Cayman S feel like it pulling more?

The thing that has always confused me though is that Ultimate, Excellium, V-Power - they all say 97RON so is the engine being retarded?

I've never put in Momentum since i used it in my JCW DD last year? It felt odd