I can't be certain about this, but i used only genuine hp cartridges on my HP 6500 printer. Fed up with the high prices, I switched to these. I have used refilled cartridges on Desk-jet printers in the past, but never on Office-jets. Shortly after installing the cartridges, I began receiving "print head failure" messages. I went through the online hints for clearing the message and returned to HP cartridges. But that was the end of the print head. With the sale price of printers being relatively low, I replaced the printer rather than attempting to replace the print head.
Again, maybe it was a coincidence, but the timing left me leery.