I just inherited Bonni '94 with 84k miles....
I'm in love with it. Nice, powerful, comfy and in pretty good condition...
Here is the question(*):

1. Since day one owners were putting Super in it... Now since gas is over $3.15 in NYC, i want to start putting Regular to save some money... Is it safe to switch?

2. The car consumes gas like it'* water. On the full tank (before fuel low alarm) i got like 150 miles. I drive about 70% city, 30 highways. Owners told me that they changed wires and spark plugs recently (about a year) and they were getting about 220-250 miles...
Any suggestions on what should i do???

Thanks everybody for your anticipated feedback...

Rookie Bonneville Owner

Since you're not supercharged, there'* no reason to run premium. You may even see better mileage with regular. How'* your oxygen sensor?

It'* not supercharged. just regular SE... Should i clean the engine? Oil? Air Filter? before switching to Regular?

How do i find out if O2 sensor needs to be replaced?


Thank You....

P.*. I know a lot of people here think what a retard but i always used subway and it worked fine for me. So any feedback is greatly appreciated.... The thread got 40 views and nobody has anything to say?

Just a guess, and this is mainly a question to the gearheads, but could the poor gas mileage be a result of running premium gas in an L27? The L27 is designed to run 87, isn't it?

You'd need a scantool to see how the O2 is doing if it'* not setting a check engine light due to poor/no performance. I'd hate to tell you to just swap the thing out if you don't know though because it'* a pricey item. However, it'* quite possible you'd notice better mileage with a new one.
An easy thing to do now though is to check your air filter and replace it if it'* dirty.

replace fuel filter?
P.*. My dad never used premium during the first 4 years of my cars life. Now that I have it, I go mostly 93, but sometimes 87...I dont see a problem unless you get engine knock

Start with a complete tune up.

PCV valve, Air filter, Fuel filter, Check your vacuum lines, Check the O2 sensor, Check your plugs.


There'* a member in NYC, Oldsman or Buickman IIRC, He may have a scantool and be able to help.

I'd be highly surprised if you weren't getting Knock RETARD though. You better hope your knock sensors can keep up and pull timing enough to compensate. Supercharged engines NEED premium. Got a scantool?

I have no scan tool. Maybe I am an idiot

you're not a retard, all questions are welcome on this forum (at least i took that impression, i've only been on for like 6 months). hell, that'* pretty much the whole purpose of the forum here.

sorry, this is unrelated to the car, but i thought it needed to be said