Originally Posted by BobThe
My personal opinion is Ford designs everything for 5W-20, but the EB's were shearing 5W-20 down to damaging levels quickly and causing warranty claims that cost money.
So they back spec'd them to 5W-30 so they would end up shearing back to a 5W-20 quickly anyway.
Ford never Back specced the Ecoboost 3.5 to 5w30. The F150 ALWAYS was 5w30. Early 2009 and all 2010 AWD's got 5w20 in the transverse vehicles (SHO, MKT, MKS, Flex). They never got back-specced to 5w30.