The Roots Universal RAI series of blowers utilize oil on the gear end and grease on the drive end. There are two primary types of grease that may be used, depending on which unit you have: a clay-based Shell grease and a synthetic Roots grease. Lithium based greases are not approved for use with ROOTS™ blowers.
Roots grease vs Shell grease
Roots grease is a synthetic NLGI No.2 grease manufactured by Royal Purple. It is more expensive, but suitable for almost any blower application and extreme conditions. Features include: excellent bearing protection under a wide range of speeds, loads and temperatures; low coefficient of friction; resistance to water emulsion and superior wear protection.
Shell Gadus S2 U1000 2 grease is an inexpensive clay-based lubricant. It is multipurpose but cannot be used in gas applications. Several years ago Shell Gadus grease replaced Shell Darina EP 2 grease which is now obsolete. Features include: non-melting; excellent resistance to water washout; good load carrying capability; good resistance to rust and corrosion.
Which grease should I use in my blower?
Old Roots product manuals recommended Shell Darina grease for general use and a NLGI Grade 2 premium grade aluminum complex grease for gas applications. Starting in fall of 2016, Roots standardized and began using synthetic grease on all units. If you have a new unit—look for a serial number starting with 16 followed by a letter—it will use the purple Roots synthetic grease. Older units could use either, but it is important to note that the two types of grease cannot be mixed as they will separate and no longer provide proper lubrication for your blower.
To maintain your Roots blower, you should continue using the same type of grease your blower has now. A quick visual inspection should help you identify your grease: Shell grease has a tan color and Roots synthetic grease is purple.