Here is my latest report from this spring. The first report on this sheet was from a fill of Castrol Edge 5W40 (previous to that Mobil 1 0W40 but I didn't do any reports on that) and all subsequent reports were on DT40 fills, with no flush between the Castrol Edge 5W40 and the DT40.
This was mostly track driving (note that DT40 is not intended for the track, they recommend XP9 but it only has a 750 mile drain interval and that doesn't work for me since I drive to the track) toward the last with street driving to and from the track and autocross. I am using Millers Nano now and will post a UOA when I get it. Although I think Millers is Ester based so I'm not sure if I will have any issues as described when mixing Ester and non ester based oils without a flush. I'm thinking about going to Mobil 1 5W50 when I run out of the Millers (I have 11 more liters...) after doing a cheap flush with Mobil 1 0W40. But this next UOA may change my mind. I paid extra to get the TBN on one of the fills of DT40 and it had plenty left.
