Regular or Super

Hello to all,

My brother just picked up his CTS in black and what a beauty it is!!!! During the explaination of all the controls inside the salesman told my brother to gas-up using "Supreme" gasoline once per month. :screwy: Persoanlly I'm a little confused cuz the specs calls for regular. What's the scoop on this??

rimfire,22

Well in the owners manual it says that Supreme is recommended, but Regular will do just fine. Don't quote me on this but I think the dealer might of been trying to say that he can run it fine on Regular but it's good to use Supreme every once in a while to clear the gunk and help it run better. Don't know if that clears it up but thats just my 2 cents :2cents: lol

Sounds like a typical car salesman. There is absolutely zero benefit to buying premium gas occasionally. The only difference in a premium gas is the octane level. Premium is made for engines that have high compression ratios that would detonate and spark knock if regular was used. THe CTS uses regular gas, the only difference using premium would make would be to your wallet. All quality gasolines have detergents included. Premium does not clean better than regulars. But oil companies always tout the cleaners in their premium gas to encourage people to buy the higher cost product. Buying an additive designed to clean injectors woud be a better idea.

We have over 32K miles on our 08 CTS with the 360 V6 with port injection, all miles done on 87 octane except one tank on premium. The engine runs perfectly. I tried the one tank of premium to see if the knock sensor and computer would advance the spark timing for more power and better fuel mileage. It seemed to make no difference.