Originally Posted by da-bees

There has been hundreds of posts regarding this subject,but I still have questions. Dealer did all oil & filter changes from purchase till 5 year warranty expired. Oil hardly turned color between 5k change intervals. After 5 years,I did two changes using Rotella 15w40 and wix 57311 filters. I used wix mainly because that is what was in it after last dealer change,so part # was there for me. Oil continued to look good at 5k intervals. After reading here and other forums that using anything other than Rancor,Motorcraft or IH filters would result in engine damage,I used Rotella with Motorcraft 3C3Z-6731-AA filter. Oil was discolored at 2k and looked auful at 5k for 2 changes. The last change was done with Rotella and a Proline brand filter my neighbor bought at Pep Boys on sale for $1.49 after mail in rebate. After 4k miles,the oil looks much better. I looked at several filter mfgrs and found that several (Wix included,not Motor craft) list different filters because of a short and long center post with or without a spring. The predominant reason given for not using most brand filters is a size difference of a few thousansents. This raised the question in my mind of why it is so widly believed that mfgrs who have made filters for decades cannot fit a filter to this engine. On the other hand,billit cap makers with less than 6 years experince with the same engine are generaly thought to fit very well.