My 2000 F-250 5.4 w/ 90,000 miles has never used a drop of oil between changes (3,000 mile) so I kinda dropped the ball on checking ya know? Today I changed the oil and per my habit first pulled the dip stick and there was no oil on it. Drained and MAY have had 3 quarts. No leaks anywhere and engine sounds as good as ever. Any idea where my oil went?? Thanks in advance.