E10 fuel

[porschedavid]

Porsche 996 4s
I see a lot of people out say that You should be using premium 98 grade fuel in this car.
Also hear a lot of people have to give there car an Italia tune up to get it though the mot emissions on 98 grade fuel.
What about mot emissions when you have to use E10?

[JFP in PA]

98 octane really isn't necessary, 91 octane with 10% EtOH is just fine, plus the added expense of the higher octane gets you nothing in performance, and cannot easily be found in many states.

[porschedavid]

Just over here in the uk
a lot of people insist on putting 98/99 octane fuel in there 996 and get the cats really hot before take for mot emissions.

[porschedavid]

For the last 5 years i struggle to get my 2005 Porsche 996 4s though the mot on emissions.I am sure the problem is lack of use and mixture of new and old fuel in tank.I only do about 300 miles in the car a year and 100 miles of that is just before mot due.

[JFP in PA]

First of all, if you are doing that few miles, you really need to drive it more! In any case, low milage cars should be adding a fuel stabilizer before topping the tank up. My personal favorite is Stabil, but there are other quality products as well.

And as for those using hyper expensive high-octane fuels to get their cats hotter, they really need to read up on the subject of octane ratings vs. burn temperatures; higher octane does not burn hotter, they are simply spending money based upon and old wives tale.........

[adias]

91 octane is a US grade. In the UK the octane unit equivalent is 95.

Porsche prefers 93 octane in the US (98 in the UK). So perhaps the OP should fuel up with 95 or better.