[coryrc]

I've never changed every two years on any vehicle.

[fragmede]

That's a useless data point without knowing how much you drive. a taxicab or police vehicle racks up hundreds of thousands of miles per year, and thus needs fluids far more often than every two years.

[mantas]

Driving style, mileage and climate. Nice and dry climate is one thing, wet snowy & slushy roads for months every year is another thing.