My father was a Ford tech for 40 years and thru following his habits I always changed my oil every 3 months or 3000 miles. As I got older and 'wiser' and cars and oil have improved I've changed to following the manufacturer's recommendations for oil changes.

Remember when spark plugs and coolant had to be changed every couple years? Well now platinum plugs and advances in coolant lets them last 100,000 miles. Oil and oil filter technology has also improved with synthetics, etc.

When I bought my 04 Honda Civic hybrid I went to have the oil changed at 5000 miles and the dealer specifically told me that it should not be done for 10000 miles. I plan to follow the same mfr recommendations for my FEH.

As far as 2 filters, I really don't know. I haven't researched it yet.