[pontiacgt]

You should have been given a rental. That makes no since you can't drive to do your car. If dealership didn't have any available they should have found you one at a rental car place. Sounds like there may have also been a bad batch of pistons going around.

 

[pontiacgt]

Dexos should not be anymore expensive especially if its fully synthetic like Mobil 1. Mobil 1 and the other brands that are dexos approved are the same price they were before they were dexos approved. This why i hate these quick lube places. They make it sound like synthetic is like double the price of regular oil and its not anymore. Even if regular oil for 5quarts is 15 and synthetic is 25, the quick lube places double the price of the change which is just weird to me.

 

[pontiacgt]

So the question is what is causing this? Bad piston?

 

[pontiacgt]

Well i have noticed if I use 89 or 93 my mileage is actually about 3 or 4 miles per gallon better. So the extra cost to me is worth it plus the engine definitely runs better to me. Everyone will have to decide for themselves. But you have to remember Gen 1 had some pistons that did this and there was also a lot that didn't have the problem.

 

[pontiacgt]

i have 3 O2 sensors replaced. They said the when the replace the last 2 about 3 weeks ago they had soot on them too. I got a check engine light and Onstar said it was a emissions issue. So far the car seems to run ok. but they need to get the reprogramming out soon if this is the issue with piston 1 and O2 sensors.