I appreciate the comments; keep them coming. I will probably take the vehicle to a local mechanic and have him give it the once over. And yes, he does Mercedes. Several years ago, I took a BMW 525 to him to check over and he seems to know his German automobiles. All suggestions made here will be given to the mechanic for his consideration.

As for the oil, because I own two diesel Jettas, I purchase AMSOIL Heavy Duty Synthetic 5W30 oil by the case. This is CG-4 and CH-4 rated, if my memory serves me correctly.

Another question. I currently drive 130 miles per day. 90% of this is highway, probably averaging 70 mph. What type of milage can I really expect? I understand it is rated for 34 highway. Is this accurate? Also, what size is the fuel tank?

SpannMan