Rotella T every 5k (after first 20k free dealer maint probably with Castrol).
This oil change it'll turn 200k.
No issues, clean inside.
Which will cause folks to complain about my 5k intervals - but it's what I feel comfortable with.
Rotella T and OEM filters is my combination.
TDT could be wonderful. I do think it's more expensive. I'd rather run an oil that meets spec and change it more often. One could spend just as much on oil analysis to know whether they can run the oil longer. I'd rather just change it. But perhaps that's just me.
Good way to start a war - an oil question. There will be lots of opinions. And someone with comments on the "multi level marketing" oil are sure to show up. It could be fine too.
Rotella is one of the two you asked about. I've been using it with no issues at all.
It would appear using 5,000 miles OCI's,that even you are true not "comfortable" with Rotella T and T6, despite VW oem recommendations of 10,000 miles.
I do agree with your procedure, just the intervals and brand are different - M1 5w40 TDT @ 25,000 miles. It however does NOT meet VW specifications. It never has. There are absolutely no issues, totally clean inside (144,000 miles) Sure instead of doing an oil analysis, I just change it.
So it is not just you.
I think one should do oil analysis if:
1. one suspects a problem (ie. G12 coolant leak to oil sump, etc)
2. is uncomfortable for whatever reasons
3. just want the information.
So in 200,000 miles you are obviously @ comfort changing 40 times, to (my) 8 times. You are correct, I am just fine with that.
The cost break down is per mile lubricated= .001145 cents (4.5 qt @ (WalMart 21. per 1 gals=) $5.25= $23.63+5.00 filter= $28.63/25,000)