I recently purchased an '06, one-owner Audi A4 w/ 2.0 l turbo engine (approx. 48,000 mi.). Upon closer scrutiny of the service records, it appears that the former owner went to Valvoline Instant Oil Change centers for servicing following the initial Audi dealer scheduled servicing. The Valvoline Oil Change records indicate that s5w30 (followed by DBBULK) oil was used in those instances. When I did some research into what grade of oil this might have been, it looks like it was a blend. My question is, if it was a blend (of regular and synthetic), what, if any, are the potential ramifications? Do I need to drain the oil and replace it with a synthetic right away? And are there any problems that I might confront down the road because of his use of this oil? Thanks for any help on this matter.