Is it okay to use Octane 90 for Opel Vectra 1993 ?
I had changed the Octane from 95 to 90 a year and half ago , and now I feel that there something wrong with the engine , there is a strong vibration on neutral, and sometimes if I am on hill and I stop , it barley moves especially if it stays too long time on the neutral position . so I tried to mix the 90 with 95 , will it work , or is it a waste of money ? Thank you in advance !