In my drag race engine, I started using 10W-30 maybe 15 years ago. That engine had an oil temperature sensor in the pan, and it was hard to get heat in the oil. Even once the water temp was 170, the oil temp was cold. It did heat up some during the run, but never got "hot" and since it was shut off and waiting for the next round, the oil in the pan got cold again. Water temp and oil temp were very different in an engine that does not run for long. Street driven was a completely different story.

I found that 10W-30 produced less ET variation in the later rounds when there was less time between rounds. Compared to the 10W-40 I used to run.