Back at the first of the year, My '00 SSEi blow the intake gasket. When I bought it in July '07, you could see that it was seeping coolant around the injectors and near the heads. December 30, '07, and not even 3,000 miles later, I decided to tear it down and replaced the gaskets. A couple days later, a little bit of money, and one torn injector o-ring causing a misfire, and the car was road worthy again. I had to replace the vacuum boost harness because underneath the supercharger snout, due to age and heat, the vacuum hoose cracked into pieces.

I just wonder if from the leaking intake, and possibly blowing coolant through the exhaust, if my upstream o2 sensor is coated and not reading accurately anymore. I just don't feel I'm getting the greatest mileage out of the car. It is winter time, and winter blend gas, so I'm not sure if that is effecting it. The car has around 138k miles on it, and to my knowledge, has the original o2 sensors.

Any ideas would be appreciated. Thanks

It'* possible that the coolant could have affected the O2 sensor. At that mileage, it'* due for replacement.

I figured that with the higher miles, it'* most likely time to change the upstream o2, just haven't felt the want too. To be honest, I haven't driven the car in almost two weeks, because my parents are driving it instead, since their '00 Impala LS was murdered when it was slammed in the rear two weeks ago.

On that Impala, the rear impact bar/bumper support was starting to crush the spare tire and the floor of the truck was almost laying on the ground. It was fairly easy to clean our stuff out of the trunk...didn't have to use the key or remote to release the trunk since nothing was underneath it holding the decklid down.

For as much as I like driving the Bonneville, at the price of gas and the money I already have invested in the car in such a short time, I really don't want to modify it. I wanted to tint the windows and do exhaust (which could assist in the gas mileage issue), but then I would have a lot more in it than whats it'* worth. It has a previous salvage title/current rebuilt title which is why I have too much invested, and have been struggling to sell it already.