So ? As long as the temperature of the lubrificant doesn't exceed the temperature that is it is rated for...
To put this in perspective:
Some time ago I searched the net a bit for endurance speed records. The following is a non-exhaustive list:
- August 1983: Mercedes 190 E 2.3-16, 201 hours, 39 minutes and 43 seconds 50,000 kilometers (247.94 Km/h average). Nardo, Italy.
- Saab at Talladega (1986 and 1996):
1986: 100,000 km with an average speed of 213.299 km/h = 468.825 hours 1996: 226.45 km/h over 25,000 miles/40,000 km. = 176.639hours- 2005 - Mercedes E 320 CDI 100,000 miles (160,934 km) Standing start 224.823 km/h ??? 139.699 mph*** World record ** Laredo, Texas 715.825 hours = 29.82 days ~= 1 month !
As you can see these cars had no trouble running their transmissions at full speed for many km.
BTW, the 1983 record was at Nardo which is a 12km-perimeter circle, so almost a straight. But Saab ran at Talladega , which has corners (it is described as a 2.66-mile tri-oval). This is a bit more effort to the differential (since the wheel speeds are very slighty different).