Yes, your coolant provides lubrication to the waterpump. Yes old coolant has an effect on the waterpump, a negative effect.
Porsche says the coolant is 'lifetime', but it's really 5yr./150k mi. whichever comes first.
Porsche doesn't make coolant, there's no magic about it. It is just repackaged w/ the Porsche logo. It is supplied by an Italian co. who's plant also makes coolant for Texaco, among others. The best coolant coming from this plant, or anywhere, which is partnered with water is 5yr./150k mi. There are waterless coolants out there which have double/triple this lifespan.
After that time, both the lubricating properties and the corrosion protection break down.
You're almost twice the expected service life, so in fact you're overdue for a flush and fill.
