Some Cat engines have a larger oil pan , that related to longer intervals between changes.
Is your oil pan steel or aluminum ?
There is also some variation year to year, posting the engine model and year would be a big help. C-7 ? C-9 ?
Genset size ? 7500 or 10,000 ?
50hrs. or annual is the interval I use for my , 7500. But I don't hit the 50 hrs. so it's always annual.