95 octane + 99 octane = 194 octane. your car will be so fast mate, do it
Mathematically speaking, you need to average them out as they are essentially the same product, but with slightly different ratings.
e.g. (95 + 99) / 2 = 97
So if you half fill with standard 95, and half fill with Tesco 99, you get 97 V power. Score!
You also get:
- A confused looking petrol station attendant.
- A big queue behind you at the pump.
- Grief off here for being a muppet.
Use 95 like the rest of us, seriously, £1.27 a litre, F OFF!