Originally Posted by mattd
Originally Posted by LubricatusObsess
Evidence? See comments on HTHS tests above.
Search UOAs for HEUI engines, or specially for the 6.0. The evidence is clear on viscosity.
Makes no sense. We're discussing synthetic 5W-40 versus mineral 10W30. Both have VI Improver additive. Not comparing two mineral oils.
4WD made the point earlier in this thread: "5w40 (synthetic) starts out with barely more HTHS than 10w30 HDEO (mineral)"
I searched 2005, 2004, 2003 Forums. The only UOA post I saw was a big one from 2003.
https://www.bobistheoilguy.com/foru...esel-oil-analysis-on-ford-psd#Post586356
I could not open the files in the post. The key reply I saw said:
"I spent a lot of time sifting through the data and concluded that there was NO significant differences between those HDEO oils. The higher wear on some trucks correlated with higher Si levels and not type of oil.
This should not be surprising though, these HDEO are very similar in weights, HTHS, and levels of ZDDP. Apparently, the type of base oil does not matter much in this NA application."
The modern CK-4 oils have boosted the antiwear additive to meet the Ford spec as well. The conclusion that synthetics are therefore irrelevant is incorrect when one considers the wide ambient range I described for this application over the 5,000 OCI.