Im new to diesels but on my last f250 I only used synthetics and have nothing bad to say about them. I wanted to continue using a synthetic on my new 6.4 but 15 qts of synthetic oil is pretty expensive, and i drive a lot. I did a hell of a lot of reading when it came to picking an oil to put in it, including a lot of searches on this forum and finally decided just to use a conventional and change it every 3000 miles. The extended intervals that the syn oils say you can go are not really good for your truck because unless your running a bypass system the filter isnt rated for those miles. And considering you can get 5 qts of ford moto crft 15-40 Powerstroke diesel oil for $10.50 per 5 qts at walmart and a mtrcrft filter online for $12 compared to what your spending on synthetic it may be less expensive to use that and just change it more often. I may be wrong but i dont know if the costs outwiegh the benifits and im curious what other members would say. I think Rotella T is $11.50 for 4 qts at walmart.
I forgot to add that the extended drain intervals recommended for syn does not take into account the amount of soot the oil collects because of the dpf. If i understand it correctly with the new dpf's oil collects the soot that is burned off during regen, thats one of the reasons that i just figured id use the motocrft stuff and just change it more often
Last edited by dc4; 09-10-2009 at 12:28 AM.
Reason: forgot about the dpf