Do go as soon as you all get a chance, to any store that sell hi mileage oils and 'any' extended oils including MB1 and take time to read the back labels.
There you will find the extended oils are not to be used in a trucks, for towing, in hi dirt conditions etc. any longer than regular oils and to change it at the same intervals that the the mfger reccomends for any no-extended or special oils.
The hi mileage oils have seal conditioners as well.
There is NO magic in these oils, no money savings because they cost more for no gain.

 

thanks