How often do you cange oil if little us

If it keeps looking clear after a 40 mile run from time to time I say 5 years but that is just me in low use engines that when started will make be ran on highway for 40 miles at less before a long shut down.

We are at 30 months on the MH and it is still clear and full after about 300 miles on this oil change. We ran it 80 miles today at 55 MPH so I will check it tomorrow for clarity.