That's a pretty conservative limit, etlsport. I run in 4W-Low up to about 4000 rpms (~40-45 mph) every winter for extended periods of time (> 30 min) with no ill effects. Beyond 4k, it sounds so whiney that I think I'm about to destroy it!

Coastie, the heat and lack of motion may have caused your VX to overheat. Running at high rpms for extended periods of time will do that to any vehicle. Bring it to an oil change place and have them test your coolant - it may need replacing...

Good luck!