Originally Posted By: Jim Allen
I think this is a great UOA. I have a 5.4L ('05) with not many more miles and my iron was a lot higher at approximately the same miles (24 ppm). I assure you, that magnetic drain plug will have little to no effect on iron readings because the UOA measures only the smallest particles under 5um.
TBN... it depends on where it started. If it started at a relatively low number, then it's doing good at just under 2 and it's probably going down more slowly. If it started high, then not so much. Shell didn't list the TBN in the couple Data Sheets I looked at just now. Me, I do a virgin UOA of the oils I use for a baseline.
Dave, this is a great UOA and I think you can use this oil with confidence.
As another poster brought out after your post here, the TBN is between 7-7.5 or so; as pqia listed the recently tested API-SN 5w30 FS @ 7.1 TBN.
So, that means we are seeing roughly 28% remaining TBN compared to starting TBN, at best if 5w-20 is closer to 7.5...
Originally Posted By: dnewton3
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The TBN is low, but not worthless yet.
There is no reason to suspect another load typical of this performance could not go another 1-2k miles. The wear is very low. The contaminants are not at all unreasonable. The TBN has a bit of life left.
Fear mongers are going to tell you this is the limit, or you should have changed it before this. All data to the contrary.
Splitting hairs, you got more than the value out of this conventional with great results, on a $10 oil change. Change by 7,500 max on this oil combo unless more all highway miles arise. There is no reason to over-think this, lol. This current FS formulation has the TBN starting to get uber depleted.
I mean really, who here consistently wants to run down to near 1 TBN? A new engine as well. This oil definitely does not have more than 2,000 miles of headroom remaining as a 'guarantee', especially in his already stated driving conditions. The more reasonable thing to do is cap at 7.5k and call it a day.
I haven't seen 1 "fear monger" post in this thread, by the way. A perfectly reasonable choice would be to change the oil now. Not sure what you are getting at there. This is a real world, dynamic situation. Yeah, driving 2,000 highway miles? It could make it. It 'could'...sure. Why push it for being an already great value run, to further exhaust a 'nearly' exhausted oil? Some 'would' argue it is 'past due' based on the TBN reading alone. Yeah, it's a new engine. The TBN and overall TAN reading is relatively low compared to a high-mileage app or especially neglected apps.
What's with the whole 30-40% of initial TBN remaining is the time to 'go ahead and change' from other sources? Some do go by that 'rule of thumb', but I don't even know why technically speaking. Maybe 'that' is fear monger. Yet, he's past that threshold. This report is singing a tenor C and you're asking to try another 4 notes higher in pitch after the fact, for the sake of technically being able to do it but there are too many variables for any one here to to 'guarantee' things.
