There is so much myth and nonsesne in this thread!!! The whole "its what my mate said" opinionated posts are the cause of so much internet 'noise'! Getting fuel from the pumps in the morning would make no measurable difference since the fuel is stored at a level where it would take days to change according to ambient temp anyway.
I can say based on facts from my own experiments that optimax and tescos 99ron are almist identical from my experience in knock resistance, however optimax gets better MPG. I have tried all fuels from 95 ron upto Cool blue 106 and GT+ 109. GT+ is amazing. It has a 4.5% oxyen content as well, so you can run richer and still get more power. I never got the full benefit from this as I didn't have enough time to play with the ign timing but I still have about 12 litres to play with but for the price of Ultimate 102 there is NO WAY I would bother with it, mix Optimax with some touliene and you would get much more than 102 octane for less than £1 litre.
I can say based on facts from my own experiments that optimax and tescos 99ron are almist identical from my experience in knock resistance, however optimax gets better MPG. I have tried all fuels from 95 ron upto Cool blue 106 and GT+ 109. GT+ is amazing. It has a 4.5% oxyen content as well, so you can run richer and still get more power. I never got the full benefit from this as I didn't have enough time to play with the ign timing but I still have about 12 litres to play with but for the price of Ultimate 102 there is NO WAY I would bother with it, mix Optimax with some touliene and you would get much more than 102 octane for less than £1 litre.