I would use normal 15-40 W motorcycle oil, grade JASO MA or MA2, alternatively SAE 15-40 SF or SG approved oil. The engine is not yet very worn after 45 thousand miles on a ten year old bike if the engine oil has been regularly change. If there is black smoke from the exhaust and you notice that the engine burns oil, then I would advise change to a single grade 40 W oil of the JASO or SAE specifications mentioned. Suitable oils can be bought from any Honda motorcycle dealership.
The 2003 Honda Civic has a 5-speed manual.
The 2003 Honda Accord has a 5-speed manual.
The 2003 Honda Pilot has a 5-speed automatic.
The 2003 Honda Odyssey has a 5-speed automatic.
The 2003 Honda Insight has a 5-speed manual.
The 2003 Honda Accord runs on regular unleaded.
The 2003 Honda Civic runs on regular unleaded.
The 2003 Honda Pilot runs on regular unleaded.
The 2003 Honda Insight runs on regular unleaded.
The 2003 Honda Odyssey runs on regular unleaded.
The 2003 Honda CR-V has a 4-speed automatic.
Honda civic 2003 -what is the best engine oil for hot weather?