Lately My 91 park avenue has been getting less gas mileage than it used to. freshly tuned, and just this morning I changed my O2 sensor to see if it gets better. When I took the old one out it was an AC delco sensor which means at 90K now it either was never changed or was just a dealer item. I replaced mine with a bosch OE unit. $19 at pep boys. but around town I have been getting maybe 17-19MPG and highway around 23-25. I remeber it being better. Is that still good for this car? I don't have the supercharged motor. Car runs great with no codes, especially after the $509 dollars for the Cam position sensor magnet replacement. what is the average i should be at? Thanks alot guys! I might add I am running 87 octane from HESS and MOBIL.

your fuel choice is not the problem, I think I get even less milage than that. I like the accelerator pedal hehe. Seriously, thats about what I get normal driving, so I guess your okay. My perferred mechanic, Morris(great guy) at the dealership, said that GM released a bulletin to run the cheapest gas you can find. I like using name brand gases like (Amoco, Hess, Exxon, Citgo) 87 myself though.

your fuel choice is not the problem, I think I get even less milage than that. I like the accelerator pedal hehe. Seriously, thats about what I get normal driving, so I guess your okay. My perferred mechanic, Morris(great guy) at the dealership, said that GM released a bulletin to run the cheapest gas you can find. I like using name brand gases like (Amoco, Hess, Exxon, Citgo) 87 myself though.


well i drove the car tonight with a new O2 sensor and mileage was like nite and day. way way better mileage like in the 20's for city and 30 for highway. A very big difference plus way smoother motor. well worth the 20 bucks. the o2's i found out don't always gives codes when they go bad. they get sluggish and just effect the mileage enough to kill you at the pump. If i was you, get a new one and take ten minutes out of your day and replace it. you'll love the difference.

no no, I think my problem is I'm having too much fun!

Tman.. ever since I got my first Buick at 18 ( 6 year old 1956 Buick Super for $550 w/40k on the engine) I have been looking for the fun that car gave me, and I think my 95 PA might be the closest yet ( when not in the shop).. plus it holds a fat guy in comfort...

Your 95 has the newer 3.8 engine, first year for it.

My fuel economy is horrible, 14mpg. I'm thinking my o2 sensor is bad...

I changed the o2 sensor while fixing another problem day before yesterday, on the chance it will improve my milage( based on the posts here).. I WAS getting about 14mpg ( it IS an Ultra after all) so when this tankfull is burned, I will know what's what..shouldn't be too soon :>)

Your 95 has the newer 3.8 engine, first year for it.

My fuel economy is horrible, 14mpg. I'm thinking my o2 sensor is bad...


After changing the o2 sensor a couple of days ago, my mpg went from 14 to a bit over 20,(mixed highway and city driving). I may have to drive to vegas to see what the freeway milage is :>) , I would have never guessed the o2 sensor if I hadn't read this forum.. thanks

I attribute most of my repairs to fixin stuff the previous owner didn't.. but now it's running sweeeeet.. :>)

oh, my book says to run 91 octane, which I do...