My 3rd oil change and went with Kendall Synth Blend I got at Big Lots for cheap $$...not bad at all for the price! Replaced it with 5W30 Valvoline Syn Power Synthetic (bogo at AA)
Filter used was AC Delco PF457G with no waviness that I saw in the same filter I pulled out from the factory on 1st change
So far I've used Valvoline A/C, Castrol GTX, Kendall GT-1 Synth Blend and now Syn Power...avg mpg is a low of 29 to high of 36...very happy with the mpg of the HHR.
Goose
Filter used was AC Delco PF457G with no waviness that I saw in the same filter I pulled out from the factory on 1st change
So far I've used Valvoline A/C, Castrol GTX, Kendall GT-1 Synth Blend and now Syn Power...avg mpg is a low of 29 to high of 36...very happy with the mpg of the HHR.

Goose
