you've asked the $118 million dollar question. That is the estimated value of the class-action lawsuit that MBUSA has agreed to settle regarding FSS-equipped vehicles.
During 1998/99, MBUSA was recommending dino oil and extended FSS oil change intervals. This led to instances of engine sludge build-up and failures. MBUSA was very clumsy in responding to the problem, unlike Toyota who quietly replaced engines due to sludge problems a few years ago.
MBUSA decided to deny the problem, then fight with owners over warranty claims, then offer "good-will" cost-sharing for repairs and engine replacements...all of which led to the lawsuit.
You will find a great deal of info on this issue at http://www.jacobsenlaw-pa.com.
MBUSA has so-far put up over $12 million in oil change coupons so every FSS vehicle can have synthetic oil installed. The remaining $106 million, as the value of extended warranty coverage, is under dispute between MBUSA and the lawyers because...you guessed it...the legal fees are based on a percentage (40-50%) of the final settlement value and MBUSA must pay the legal fees.