I've got an 04 Deville DHS, 66k miles. It's acting a little sluggish, and the mileage has gone down considerably 10-15%

I thought maybe O2 sensors, but don't want to just throw money away.
I have not had any codes run, or brought to mechanic yet.
Any suggestions appreciated.
Thanks
G

 

Check for codes. It is winter drop in MPG maybe normal. Check air filter, add BG 44K or many members favorite Lucas to a full tank of "Top Tier" regular grade gas. See if it helps.

 

OK, will do. How about SEA FOAM in very low tank? Always use BP (Amoco)
Thx
G