If you drive normally and use conventional oil I recommend you change oil and filter every 5,000 miles. If you use Synthetic oil the change it every 7,500 miles. Use a quality filter.
140000 km
Around 5,000 miles with conventional oil and 7,500 with synthetic.
The average Miles per Gallon for a 2008 Honda Odyssey is 17 mpg city / 25 mpg highway.
15000 miles
The EPA range estimate for the 2008 Honda Accord is 407.0 mi. in the city, 573.5 mi. on the highway.
The EPA range estimate for the 2008 Honda Pilot is 326.4 mi. in the city, 448.8 mi. on the highway.
The EPA range estimate for the 2008 Honda Odyssey is 336.0 mi. in the city, 483.0 mi. on the highway.
The EPA range estimate for the 2008 Honda Ridgeline is 330.0 mi. in the city, 440.0 mi. on the highway.
The EPA range estimate for the 2008 Honda Fit is 302.4 mi. in the city, 367.2 mi. on the highway.
The EPA range estimate for the 2008 Honda Civic is 343.2 mi. in the city, 448.8 mi. on the highway.
The EPA range estimate for the 2008 Honda CR-V is 306.0 mi. in the city, 413.1 mi. on the highway.
According to Honda, no, it is a lifetime fluid. My advice is to change it every 75,000 miles.