I would tellt he dealer if it isn't an issue, then why dont they check the guides and show you them.
I'm no pro though, but thats what I would look to have them do. it can't be that hard for them to pull the valve covers and check the guides..
'92 300CE - Sold
2004 C240 - C7 Wheels
2015 ML350 - P1, Pano, Ash poplar wood, Sport Dinamica interior, Running Boards Keyless go.