Granted Patent
Utility
US 4,900,875 · App. 07/299,387
Polymeric viscosity index additive and oil composition comprising the same
Inventors:
Robert B. Rhodes, Arthur R. Bean
Patented Case
View Patent ↗
Granted: Feb 13, 1990
Filed: Jan 23, 1989
Inventors
Robert B. Rhodes
Arthur R. Bean
Assignee (at issue)
SHELL OIL COMPANY
This patent predates the USPTO's electronic file wrapper — prosecution documents from this era exist only in the Patent Office's paper records. A certified copy of the file history can be ordered from the USPTO's paper archives.