I don't think VRP is a long drain oil but TBN on it's own is not a good indicator of drain interval. Do a search on TBN. There is a lot of information on its value or lack of. A better value would be change in oxidation rate and wear metals + TAN. TBN can stay at 2+ for quite some time. This oil's oxidation virgin is around 7. It's now 11. So it's barely moved in 5k miles. I'm not suggesting to go further but technically speaking the TBN is not an issue here at all.
Most of all the mid/low SAPS oils have a starting TBN of 7-8 now. ESP, Mobil 1 EP etc. They will hover around 2 for a long time and remain stable.
"TBN in an oil is primarily derived from the over based metallic detergents in an engine oil. One of functions of these detergents is to neutralise the acids formed by the oxidation of base oil.
And this is where TBN gets to be a poor predictor of oil life. 10 TBN's worth of detergent in a Group I oil (old fashioned mineral base oil) will be depleted much more quickly than 10 TBN's worth of detergent in a Group III based oil (severely hydrocracked base oil). Put simply, if the base oil resists oxidation, it doesn't form carboxylic acids and so makes no call on the TBN reserve.
The other thing is that TBN depletion isn't usually linear. On industry standard tests like the 100 hour/150°C Sequence IIIG, TBN usually depletes exponentially and in severe cases you might find that half way through the test, the entire TBN reserve has be used up, such that oxidation resistance is carried by supplementary Antioxidants in the oil."
"One other thing...
Most folks would consider an engine oil to be shot when the TBN reaches 2 - 3. This isn't actually the case. An oil can function quite happily with a TBN of zero.
The thing you have to remember is that oil formulators don't tend to focus directly on stuff like TBN depletion, acid formation or oil oxidation. What they're really concerned with is the onset of exponential viscosity increase. For many of the lengthy, industry standard engine based oxidation tests, it's both impractical and uneconomic to just use over based detergent to control oxidation. Given how fast it can deplete, you might need an oil with a starting TBN of around 20 to keep the TBN above 2 at the end of the test!
For this reason, modern oils contain a cocktail of various Antioxidant chemistries, each of which plays a role in keeping the oil from 'breaking' long after the TBN reserve has been exhausted.
Just to be clear, there's nothing wrong per se with changing out your oil when the TBN hits 2 - 3 but if you do a UOA, and find the oil's TBN is zero, it's not something to freak out about."