Is it safe to use non-HP or refilled ink cartridges in the HP OfficeJet 6950?

Using a non-HP cartridge or a refilled cartridge does not automatically void the printer warranty or any HP support contract. However, if printer failure or damage is attributable to the use of a non-HP, refilled, or expired ink cartridge, HP will charge its standard time and materials fees to service the printer for that specific failure or damage. (Page 3)