That’s great Brandon, thanks. But how many hours or miles on a typical weekend? The reports include the “health” of the oil as well as indicators of possible issues with the engine. Was there anything on the health of the oil after one weekend to necessitate a change? The simplest metric is typically viscosity. Have you had a fresh sample of your particular 3:1 concoction (I like that BTW) analyzed to establish a baseline?
I'd say anywhere between 6-9 hours dependent upon test day and double-dipping. The series I ran specifically during that time was a 30m qualifying and 45m race so that combined with a standard SM group entry and the test day got me to the greater number of hours.
I did have a TBN analysis done to provide a comparison, I'll see if I can dig it up if you're interested.
Regarding the interval itself, I'm sure there were hours left on the table but this was an experienced race engine builder (decades of various race builds - Nissan, Honda, Mazda) and had his own historical data to support his "program". You are implying correctly that I did not attempt a "2 weekend" interval, in an effort to validate the expertise, but that's why I used him: if I'm paying money for his knowledge, why would I second guess him on a simple maintenance item that costs me $18 and 30 minutes after the weekend?
I've only known of one engine he's built & installed that's failed mechanically** and that was due to the driver not recognizing when your water temp/pressure gauge is accurately showing you have no coolant. That driver's engine failed on the 2nd to last lap of a 20 minute race. My engine ended up going into another competitor here in the NE and it's being ran on a regular basis with multiple clubs up here.
Oh, and he's never had an engine fail tech inspection and he's had plenty torn down in the past 10 years.
** I am qualifying it because he used to do build & ship but his last experience selling to someone (where he didn't perform the install) who didn't follow his instructions (for either break-in or maintenance) called after a couple of weekends asking for some money back due to lack of power or mechanical failure.