I have a question about engine cruising RPM vs engine wear. The new car I am buying is a 5 speed manual...

I have a question about engine cruising RPM vs engine wear. The new car I am buying is a 5 speed manual, and at highway speeds it runs at about 4000 RPM. I am used to my older 6 speed that cruises at half this RPM on the highway, so 4000 seems high. I do a fair bit of highway driving so I am wondering, will an engine that cruises at 4000 RPM on the highway face more engine wear than one that cruises at 2000? Or am I being irrational and worrying for nothing? The engine uses 0W20 oil if that matters.

No but more fuel.

In theory anything under the red should be fine for the engine, but I'd imagine in practice faster rotation means higher wear.

Source: my ass

Doesn't matter even a little bit. Economy cars of '80s-'00s, and to a lesser extent today, frequently turned 4,000rpm going down the highway. They did this by design, for twenty years and hundreds of thousands of miles, without complaint.

Not necessarily, even though the engine is spinning faster it is at a lower load % and uses less fuel per rotation

I used to think that RPM = fuel consumption but it is actually a lot more complex than that

Engines have an optimal wear zone. 4000rpm is getting pretty close the the edge of that zone. There's a reason why commercial and industrial engines are big and low rpm. I'd be more worried about your ears having to listen to 4000rpm for hours on end.

Im just going by my own shitbox 5 gear that soins at 4k
City driving consumes less fuel than highway.
Our golf 7 tdi lasts much longer

my shitbox is between 3500 and 4k when im on the highway and it gets 30 mpg all day. these little motors are made for it. 130k miles and counting still running fine

I accidentally shifted from 5th to second and the RPMs shot up to 7000 but 1500 below red line. Is my engine kill?

No