Hey folks,
Having trouble with my baby, 1998 Bonneville SE.
Drove it around the block this morning, she had a very rough idle, had a nasty shake, and was misfiring (I think) leaving backfire residues on the ground that seemed to stick around (thought there might be some oil in there). Power loss was occurring as I drove it, gave it gas and it struggled, then recovered, then did it again. It also was leaving a burning oil smell, and when I checked the oil, some real hot air was coming out (way too hot oil). The CEL was on already (O2 sensor needed replacement, maybe thats it?) but started flashing when engine was having problems. I'm useless at diagnostic, but have always DYI'd my cars (when possible lol) and really hope this is something I can fix.
Anyway, does anyone have any suggestions about this? Car has 250k on it, but was running great up until this point.
THanks, Tom

OH, I should mention that I just changed the oil, and the coolant was high.
Thanks

What was the SES code? Have you checked the PCV valve?

Havn't checked the code after this happened, just happened this morning and have to borrow OBD from a buddy. How would I check the PCV valve?
Thanks, Tom

https://www.gmforum.com/t279060/

Take the PCV valve out and shake it, if it rattles, it'* good.

Will do tonight, thanks
Hope its a dirty PCV, nice and cheap!