2009 987.2 / 2.9: long term use of 95 ron?

[911hillclimber]

On a recent long Euro Tour I used 3 successive tanks of 95 ron in my 2.9 Boxster.
It usually is fueled by Shell V Max, 99 ron.

One tank abroad was TOTAL 100 ron and I could tell no difference from 95 to 100 ron tbh.

I do not rag the car, never hit the rev limiter etc and get around 32/34 mpg.
Anyone with a technical understanding of long term use of 95 ron (say constantly Shell) in the car please?

I think the ethanol content may be higher, but the TOTAL 95 ron was 5%, their 100 ron was 5% also.
Thanks, Graham.

 

[legin]

Here goes the short version. I was in the refining industry most of my career. So you need to understand some of the basics. There are four key elements. RON/MON , Biofuel, detergents, location a bit more to it than this but keep it simple.

Location - Almost all the base fuels are supplied regionally based on where the refinery is closest with the exception of the premium grades of some tier 1 suppliers. Some base fuels are better than others so fuel in particular diesel can perform much better depending on where you live, I cant divulge Im afraid. This means its all the same stuff with the exception of the not to be underestimated Additives

Additives /Detergents - this what cleans your intake and really a function of the brand. Supermarket fuel has these but not as much as the tier 1 suppliers. Also some additives are performance enhancing.

Biofuel - This is the Ethanol which helps with ron/mon but does nothing for calorific value and in large quantity synthetic rubbers and plastics dont like it. The high octane is the so called protection grade in other words it there to run in engines that cant cope with ethanol as well as its higher performance attributes.

Ron/ Mon - The big one in your question. So provided your car has electronics ie knock sensor to monitor detonation then it will do no harm as the ecu retards the ignition. So in theory you lose power but this assumes that you only get 95 when you buy 95 but often there is giveaway meaning octane is higher like 96 for instance. If you hear detonation or lose lots of power then up the octane.

If you intend to use for example shell 95then that would be a good decision and as you rarely push your car hard then you will get virtually no benefit from a premium grade.
I used to run a car which wasnt able to retard ignition but 97 ron. So I used to do my own blend t the pump to save a few quid and that was half 95 and half 99 which = 97. Its exactly how its works.

I run my 3.4s on only 95ron and happy to use supermarket fuel and live in cheshire. If doing track work then I would up the ron to 97 +

The only engine I ever needed 97 ron to make work was the bmw m54 because it lost so much power from the ignition backing out.

Hope this helps but you will have no issues whatsoever

 

[911hillclimber]

Fabulous post, and exactly what I was after, so I thank you very much.
I'm sure it will help many others too.
I seem to gravitate to Shell products, fuel and oils. I was told some time ago when I ran/hillclimbed a 370 bhp Subaru Impreza that Shell fuel ron was very consistent.
I thrashed that engine (2 litre) and then some and it ran perfectly with Shell.

Thanks again,
Graham.

 

[Joejoshem]

I agree this is a really helpful explanation.
Thanks, legin.