SE light and shifting hard
I know this has been posted about a ton of times, but I wanted to see if I could find some consolidated information as we would like to see if this is doable on our own instead of taking it into a shop. I have a 2007 G6 V6. I had my oil changed a week ago today and ever since it has been shifting into 1st and 2nd (and sometimes 3rd) really hard about 50% of the time. A couple days after it started the SE light came on and will go off at random times. Obviously this seems as if it is a common problem. I haven't had the diagnostics ran to get the code yet; I probably will tonight. From what I have been seeing, it seems quality of oil or something similar could also have caused the problem?
Can someone tell me exactly what they did to search out the problem and correct it? Any help would be appreciated.