it doesn't affect computers adversly. oil in a car is much more important than thermal paste on a CPU.
in fact, I'd compare oil in a car to what sort of cooling it has. if a car had low oil, it would be equivalent to a really tiny heatsink that barely gets the temps down.
thermal paste can give slightly lower temperatures, however a CPU can function completely fine without it.
the ony parts that would wear out are the mechanical parts (especially the hard drive)