6k already on the 150 - impressed. But yes, pays to check regularly in dirt conditions. A 'service' only seems to be changing the oil and filter regardless of Km's, need to keep a record and check specific items when due yourself.
If you're riding behind other vehicles in dusty areas, you really should check it every day.
Better still, check it & re oil it on at least a fortnightly basis regardless.
It doesn't take much dirt to "dust" an engine, then you're up for a new top end.