Just wanta add::

ur 2008 SE5 with 43,000+ miles never had the valves checked or adjusted. When the tech checked them before reselling it after I traded for a 2010 RT, he said the valves were perfect. Now the RT is approaching 10,000 and all I am doing is changing the oil and filter, and soon (about 11,000) a new rear tire...going with a BFG G-Force. Yes, the belt is a bit loose, but the new tire will take care of the adjustment.
In case you're wondering, I have used Royal Purple 10W40 Synthetic automotive oil in both Spyders...the 2008 SE5 for 40,000 of the 43,000.