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Fuel type for a 991

A

Adrian72

New member
Joined
20 Jan 2012
Messages
16
Can anyone help please.
The handbook on the 991 suggests using super unleaded or >98 Ron.
However it's says if you use regular unleaded (95ron), then engine will auto adjust the timing.
Looked at threads on this forum and they suggest it's not that simple but I wondered if the new 991 can cope better?
Any suggestions?

Thanks,
Adrian
 
This has been an ongoing topic here.

Most on the forum would agree that V power or Momentum will be the best. Porsche themselves do not recommend 95 RON as the first option.
 
Thanks,
As I thought.
I am not sure what the car has in it, this will be its first fill up. Will I be ok mixing fuel types doe you think?
 
The handbook is saying you should always use 98+, but if you can only get 95 then the car is smart enough to protect itself from any damage by going into a drive safe mode. This modifies timing, reduces power and your economy will drop too. Your car will revert back to normal performance once it is satisfied the fuel it is receiving is back up to 98. this may take a full tank or more of higher grade fuel else there are alternative ways to force a reset sooner.

If you are using 95 then you should switch back to 98 as soon as possible to get the best from your car...
 
Manual and fuel flap say 98 RON, and for good reason.

Not only do you lose power, but that cheaper fuel is used quicker.

The engine will run hotter too on 95 RON, and that is not good for all sorts of longevity, thermal stress and reliability reasons.

Expect to lose about 30BHP and a load of torque if you use 95 RON fuel on a Turbo (less so on an NA, but still more than 10 BHP).

95 RON will also result in increased consumption at a steady speed - by up to 2-3mpg (so an easy 10%).

So a real false economy to fill with the cheap stuff.


The DME can "learn" the fuel grade (and atmospheric fuelling effects), so if you are planning on using a higher grade than in the last tankful, do a reset for immediate effect (rather than waiting for up to half a tank to passive reset).


DME reset is via key, Throttle Body reset is via key

Reset via key requires turning the key to ignition "1" (the position when all the lights are on on the dash) and leaving it for 60+ secs (DO NOT TOUCH THE THROTTLE PEDAL), then switch off for 10+ secs and you should be able to hear a few clicks and whirs from the engine bay as it recalibrates the adaption values.

Adaption must be performed when ambient temps are > 10°C
 
thankyou for your advice.

Spoke the OPC when they opened today and they confirmed what everyone seems to be suggesting - stick to 98RON

Ta.

Adrian
 
The fuel selection on a 991 seems to be even more critical than it was on the 997. I have had a rough running issue on mine by filling up at a certain Tesco 99 garage, and the car runs hotter, oil temps reaching 105 deg, but when running on the fuel from the Tesco local to my work, the car runs smooth, and the oil temp is normall around 91 deg.

This of course is not scientific fact, but I have now done 4000 miles, and only filled up at these two petrol stations.

Just wish there was a way to test that you are actually getting the octane rating that you are paying for!
 
Posted in error.

Red strikes again (not that white is any less effective).
 
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