I was reading the Userguide today and found the following bits of trivia regarding Inks and the cartridges.
With the ability to disable the ink level detection and the direct mention of filled tanks indicates Canon has a least thought of the refillers amongst us.
From Canon...............
Do not remove an Ink Tank to shake it once installed in the printer. Ink may leak out.
We recommend using up an Ink Tank in the course of printing within six months after breaking the seal. Using an old Ink Tank may affect the printing quality.
Do not remove the Ink Tank if the printer is not used for a long period (a month or more). Ink remaining in the printer may become clogged and affect the printing quality.
Disabling Ink Level Detection
Ink level detection
Ink Tanks specified for this printer feature an ink level detection function to prevent the ink from running out during printing, which prevents printer damage.
This function will not work correctly if you use filled Ink Tanks. As a result, printing stops. Thus, before using filled Ink Tanks, you must cancel the ink level detection.
Printing with the ink level detection canceled may lead to printer damage and printing problems. Canon Inc. is not liable for any damage that may occur as a result of using filled Ink Tanks.
Caution
After ink level detection has been disabled, this function cannot be reactivated for the currently loaded Ink Tank. To use ink level detection again, replace the Ink Tank with a new ink tank specified for use with the printer.
Repeatedly removing and inserting an Ink Tank may damage the connection between the Ink Tank and the printer, which may cause ink leakage from the Ink Tank and damage the printer.