Ah, just realised I responded to your comments re the code 82 yesterday. My dealer said entirely the opposite of yours, i.e. there's no problem continuing driving with code 82 on. It's only an advisory message. Geez, can't believe they didn't know what code 82 was - it's even in the owner's manual!!! So much for Chevy dealers. Begs the question - "Do they know what they're doing?" Did they renew the filter & has it solved your problem? They could also have re-used the existing oil couldn't they as there's no way an oil change should be necessaruy after 4k? Hope they didn't charge you.