1997 Cadillac Deville

Last year I bought a new car and gave my old car (1997 Cadillac)to my Grandson to drive. The information on the Cadillac said to use premium gas, which I always did. My Grandson works part time and goes to school and tries to save money where he can. He asked me if he had to always use premium in the car or could he use regular all the time or some of the time. I was hoping I could get an answer from Car Talk.


Donnie Pope

Donie, if it says premium, you use premium.

Your grandson could save money by driving as lilttle as possible and slow rather than fast. A Cadillac simply is not an inexpensive car to own and operate.

TRY a tank of regular and see what happens…5 octane points will NOT change the course of history…If he can not detect any spark knock (you can plainly HEAR IT) then he is NOT damaging the engine.

Most “Luxury Cars”, when on their second and third owners, seldom get premium fuel. They all seem to survive just fine and “engine damage caused by using regular gas” is NOT what sends them to their grave…

There are two, and maybe three places to check. The owner’s manual will say whether it is recommended or mandatory. This is probably also inside the gas filler door on a sticker. It may also be on a sticker next to the gas gauge. He probably drives little enough that annual expenses are less than $100 to use premium.

He could be losing the money he saves on buying regular to decreased fuel economy, though. Kid should run premium if it is designed for premium. He saved plenty of money by getting a free car. If he still wants to cut corners, he should do his own maintenance.

Grandpa, buy the kid a tool kit and a set of jack stands.

Thanks for all the feedback/opinions.

Thanks for the feedback

IMHO, if he’s that concerned, tell him to buy a bottle of octane booster with every tank of gas.