As long as the oil is in good order and the vehicle is regularly maintained, I don't see a problem with revving the engine. I regularly run mine out to the 6,200 rpm red line and I don't believe I'm doing it any harm.

I have seen it suggested that you can save an enormous amount of engine wear by changing up before the last 200rpm of the engine's range, which suggests that going up to 5,000 or 5,500rpm won't do any harm.

On highway journeys I like to keep my speed bewteen 90 and 120mph (conditions permitting), which means a steady cruise at up to 5,000rpm. I once ran it between Paris and Calais at 130mph on the cruise control, stretching to maximum speed on the long straights without any concerns.

It can often do more harm to make the engine labour in too low a gear.

__________________
JJ Rodger
2013 G350 Bluetec
1999 SL 500
1993 E300 diesel T
1990 190