Just a suggestion.
Valvoline SynPower, 5w-40, European Blend, for MB, Porsche, VW etc... is on sale at Advance Auto Parts this month, along with a Bosch Distance Plus Filter for $30.99 before rebates of $7 and $5 for Valvoline and Bosch, respectively.
For some reason Advance does not have the 5w-40 SynPower, full synthetic, European Blend in stock.
So....you could try what I did....I brought the Flyer from Advance to Walmart for a price match on the Advance special.
Some Walmarts, carry this oil, not all, and they now carry the Bosch D+ filter. Walmart honored the special.....which after Rebates from Valvoline and Bosch....works out to $18.99 for 5 quarts and a great oil filter.
Napa auto parts also has the Valvoline 5w-40 oil on sale for $5.69 a quart and has a Valvoline rebate for $1 a quart up to 12 quarts for synthetic and all blends or Valvoline. So after rebate...each quart is $4.69.
You could get 5 quarts and the D+ filter from WM and another 12 quarts from NAPA auto parts.
I'm sure that your daughter and her husband, or partner, could skip a few Starbucks coffee's and pick up these deals.