I never understood why? I am running mobil 1 synthetic with a fram filter... no problems here.
Poor filtration, it's been discussed here. I read a report comparing oil filters Fram was at or near the bottom of the list. I use K&N, expensive and worth every penny IMHO.
1999 Toreador Red SVT, DOB 4/22/99, 2005 Of 2760.
"Many posted questions are answered by farm boys"