Yea thats what i ment by carbon build up.
The soot if I am correct is unburnt fule/carbon
I might be wrong
I might be wrong
Last edited:

Tesco momentum uses 5% ethanol. UK shell v-power has no ethanol in it.
Ethanol provides a better burn and has a higher calorific value than petrol. So more power and mpg.
Therefore momentum is better. Also in all tests i have seen momentum has made the best power even sometimes better than BP ultimate 102 octane
UK 99 ron shell v power still has no ethanol in it only 100 ron v power uses an e10 blend of ethanol it is very rare in UK