Fellow oil guru's...I recentely ran a UOA (it is posted on the UOA forum under the name "ponch" ) on my 2007 duramax LBZ truck(modified with computer tuner), using rotella 15w40 CJ-4 dino oil for just over 9,000 miles this past summer which included heavy towing/driving this past summer.....to say the least the results were noting short of spectacular! NOW I am on a mission to run the rotella synthetic T6 5w40 for as long as possible to try and see just how long this oil will last in my pickup...the TBN of the UOA of the 15w40 triple protection after that run was at 7..in which blackstone labs commented back to me to try "11,000 miles next run on the same oil"...I am looking for fellow users of this T6 oil to guide me as to how long you think that I can safely stretch this interval? (without bypass filtration) I have learned VERY much from this website since I have been a member...and have been following the member's "dnewton" and "arkapig" on their results from running 10w30 HDEO's in their own duramax pickups (in year round temps) with great results! "Dnewton3" ran a UOA with 10w30 rotella dino with great results while "arkapig" ran a UOA of 10w30 delvac with also great results! I average no less than 25,000 miles per year...and am wondering if any of you think I could stretch this oil to this amount of miles WITHOUT bypass filtration? For this run I am currently using an Amsoil EAO oil filter which is good for the 25,000 mile/1 year mark... I want to justify the cost of using synthetics like this oil, (as I have learned that synthetics are a waste of money unless you greatly extend their use)...please chime in all! Thank you in advance!! -PONCH