Warranty? Okay, I didn't void it by doing the first change at about 500 miles, but after that...
Normally I do the change in the late fall, then it's ready to go in the spring. Except for the year I forgot and both ended up with exactly two years on the oil. Sent samples to a good lab, then had a very knowledgeable person analyze the results.
Both cars had about 500 miles on them in those two years, and the PUP passed with flying colors. Good for at least another 3,000 miles I was told.
But, they're never short tripped or, gulp, cold started to impress people. Instead they're generally driven at least 150 miles once started. That does make a difference.