I can't get too exited about gaining a couple of bhp. With more than say 500bhp engines I don't change the oil every time I use a car, I do change it when doing so will add 7 or 8 bhp. Similarly I don't rebuild engines until they get me 4 or 5 more bhp than an oil change.* On most tracks the handful of bhp we are talking about is only noticed on the longest straight and as someone has already posted re the Enzo, worth very little in mph terms. I'm on part throttle a lot of the time on anything but an Oval so it's not that much of an issue to me.
I do an oil change on a new car, The gain is, I suspect, meant to reflect the use of a thinner better quality oil. After-all reduced engine wear is not usually at the top of the reasons why an oil is used in a racing engine. low viscosity and ability to deal with high stress on a hot engine are more important than reducing wear at start up and when cold which is an issue with road going engine oils. My wife's car used to run 90% of the time at below optimum temperature as her commute to work was only 5 miles each way, that demands a multi-grade and stickier oil,
than that needed in a racing engine which does almost all its work at high revs and fully hot!
* I suspect this is too early too!