No. First of all, a good quality octane boost like Amsoil or NOS costs about $10. In addition once you add it to your tank, you cannot ensure perfect mixing like that from the pump. Some places will be really high in octance and others will be 87. Just stick w/ 91 octane, nothing less and nothing more. By the way, I ran my 89 300E on 87 gas for about 7 years and now I switched to 91 and I have no problems.