MK5 Golf GTI

All Things Mk5 => Mk5 General Area => Topic started by: Jons1001 on September 29, 2021, 02:56:48 pm

Title: Safe to put 95/97 ron fuel in '99 ron car'?
Post by: Jons1001 on September 29, 2021, 02:56:48 pm

Anyone know if this will be ok for a tank or 2? The car is originally from Japan so always been ran on 99 ron fuel (says it on the fuel cap) but has also been mapped and only had Tesco Momentum 99 in it since. Would it do any damage to put a tank of normal unleaded, or 97 ron (Sainsburys, BP) Cheers

Title: Re: Safe to put 95/97 ron fuel in '99 ron car'?
Post by: garrardrj on September 29, 2021, 06:41:47 pm

Won’t do any harm. It will run poorly until the ecu gets used to the lower octanne.

Title: Re: Safe to put 95/97 ron fuel in '99 ron car'?
Post by: GVK on September 29, 2021, 09:23:41 pm

I'd drive it, it wont explose , but wouldnt thrash it.....

Title: Re: Safe to put 95/97 ron fuel in '99 ron car'?
Post by: pudding on October 01, 2021, 11:03:23 am

If it's been mapped for 99, it will likely run into detonation if you drive it hard.  Just tread carefully with the throttle until you can get 99 in there again.

I don't know why tuners mess with the ignition timing.  They should just leave it as VW set it, which gives you more scope for running lower octane fuels.