Hello, I am looking to buy my first Cadi (1990-2000) and need to know about their use of premium fuel. Which use regular and can I run regular in any that recommend premium? Thanks.

I believe that in 2000 the N* was engineered to run on regular gas. Most N* have a knock sensor that retards the timing to allow you to run on regular.

spend the extra 10 cents a gallon and get premium. its worth it.

If you want the best performance from your gas dollar than get the 2000. Running regular in the others is do-able but not preferred.
However, assuming you get 20 mpg and you average 12K miles / year, at today's prices the 2000 saves you $150/yr. Again assuming you want max performance with recommended fuel.
Just another way to justify an '00 or later. Your mileage may vary...

Some early 90's use premium, period. Mid-late 90's recommend premium, and 99- on allow you to use 87, 89, 91, 93. Whatever floats your boat. Running higher octane fuels in an adaptable engine does not necessarily equate to higher power output.

My 1998 STS has always (except on a few necessary occasions) been run on Premium 91 Octane fuel. Not only has the gas mileage been good 15.9 mpg City 26.7 Hwy, but the car runs better and seems to have greater horsepower.

I was told by a tune-up shop (TUNE MASTERS) at my 100K major tune up, that the spark plugs look as if they could have been used for 20K or more miles. He indicated his experience of having tuned over 100 Northstar equipped GM cars, including the Oldsmobile Aurora, and he informed me that the 87 Octane fuel, scorches the plug, and he believes the cylinders of the engines themselves.

The 2000 and newer engines were re-designed to operate on lower Octane, and have enhancements which allow safe operation on the cheaper/methane containing fuels. If in doubt consult your owner's manual.

With a premium stuff the car responses quicker .Is it worth ? Yes but that's a relative .
Another note: After having my 'lade's PCM Tuned I was recommended to use premium .With a tuned PCM you get better results from my experience

:confused: Just exactly what does the above post have to do with anything related to DuneOH's thread starter question ????

You're in this forum to supply information and critique, not to see yourself in print 50 times a day on a worn out Ringling Brothers; Barnum and Bailey circus poster.

I hate to rain on your party, but 99% of your advice is actually "I Love Me" material.

i think he was saying that the car responds better with premium and its worth it...

Some early 90's use premium, period. Mid-late 90's recommend premium, and 99- on allow you to use 87, 89, 91, 93. Whatever floats your boat. Running higher octane fuels in an adaptable engine does not necessarily equate to higher power output.

^^^^
I thank you kindly for this concise analysis.
What do you think about the fuel requirement
would be on the 1994 Concours? (which I believe
was the first Northstar they put in a Deville); since,
I am close to getting one for the winter.

(BTW- I usually run my 2000 Deville on regular,
but have used premium for the detergents; mileage
improved ;but, power was seemingly unchanged).

Any advice on the 1994 Concours would be appreciated.

Best Regards,

TomDeville:cool2:

Thank you to everyone for your answers. I now have a better understanding on this topic.

Thank you for your reply (s). I now have a better understanding of this topic.

Thank you for your reply (s). I now have a better understanding on this topic