Words from HP:
Use EconoMode (draft) printing to print with less toner on each page. Selecting this option might extend the life of your print cartridge and reduce your cost per page, but will reduce print quality.
HP does not recommend full-time use of EconoMode. If Economode is used full-time when the average toner coverage is significantly less than five percent, it is possible that the toner supply will outlast the mechanical parts in the print cartridge. If print quality begins to degrade under these circumstances, you will need to install a new print cartridge, even if toner remains in the cartridge.
How to Save Print Cartridges?
Highlight the Printer name, such as “4250INTERNET”.
Click the tab “Paper/Quality”,
Click the checkbox of “EconoMode”.
* The above guide is for HP-4250 Printer, and settings on Windows 2000 Pro. Similar setting page on other Windows OS.
More detail info of HP LaserJet 4250.