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Anon
By tnaseem | AA Member | 6 Posts | 15 March 2014 at 11:17pm

Hi,

We've just bought an Audi TT for the wife. It's a 1.8T 2005 model, imported from Japan. The chap explained we should be putting in 95 octane fuel, but I was wondering if we'd be okay with 91 octane?

As an aside, we had the same advice for my Subaru Outback (2005) which you chaps advised that 91 was perfectly fine. So, advice on the Audi would be appreciated!

Cheers,
Tarique.

Anon
By Donavan | AA Expert | 1049 Posts | 17 March 2014 at 10:01am

The information I have states that this vehicle should run on premium fuel - 98 octane.

Anon
By tnaseem | AA Member | 6 Posts | 17 March 2014 at 10:46am

OK. Thanks.

What are the drawbacks on running it on 91 or 95? Just out of interest.

Anon
By Donavan | AA Expert | 1049 Posts | 17 March 2014 at 12:59pm

The octane rating is the amount of compression the fuel can withstand before detonating and by using a lower octane fuel than recommended, In the short term it's unlikely to do any harm but if you use the lower octane fuel for long enough it could cause engine damage. The lower octane fuel will cause pre-ignition to occur inside the engine (knocking), the engine management system will try compensating for this, which will cause reduced performance and increased fuel consumption.

You will not gain anything by using a lower than recommended octane fuel so it's best to keep within the manufacturers guidelines to prevent any problems.