TDI : "safe" RPM ?

I would say as long as it is below the redline, properly warmed up, in good condition, with proper oil pressure, everything in tune. Then why not... make sure to watch your engine temperature tho.

when I'm on the motorway doing 80-90+ mph, the rpm is regulary at 4000rpm. But then I'm driving a petrol and i know diesels weren't made to rev as high as the petrol.

If you're talking about "truck" diesels, that's true. Modern car turbodiesels, however, have no problem hitting 4000 rpm for long periods of time.

sd

I'd say running it at ~ 50-60% of redline for long periods of time is OK. Above that, I'd be weary.

My diesel is computer limited by the automatic tranny to around 4400rpm or so, that is when it will upshift if I have it to the floor (never really do it, just wanted to see how a diesel reacted to a flooring when I got the car, I find it accelerates quicker if you let the speed build up and have it shift at like 3900rpm)

I don't know what the limit is by the computer in neutral.... redline starts at like 4800 or so...

Yeah, that's so true... The higher you rev (on average), the quicker your engine ages. I wish cars didn't just have odometers, but also total rev counters (i.e. 100k miles averaging 2500 rpm is a lot different from 100k miles averaging 3500 rpm).

I think that if you don't rev the VW engines then that could hurt them too! JMHO

later, dave Reminder........ Before you criticize someone, you should walk a mile in their shoes. That way, when you criticize them, you are a mile away from them, and you have their shoes. Frieda Norris