Esso Avitat @ Ottawa Macdonald-Cartier International Airport

The Esso and Shell on the south field are fairly expensive for fuel and have high parking and ramp fees. Esso used to waive the ramp fee when you were meeting customs there, but I don't know if they still do that. If you don't need the full FBO red carpet service (and aren't arriving late in the evening), the Ottawa Flying Club on the north field is a cheaper option for fuel and parking.