AMSOIL Adds Donaldson Filters for Heavy Duty Applications

SUPERIOR, Wis.--May 2, 2005--AMSOIL INC. (www.AMSOIL.com) of Superior Wisconsin announced today that it has made available to its dealer network Donaldson Company, Inc.'s full line of aftermarket Heavy Duty Air, Oil, Coolant, Fuel, and Hydraulic Filters. The advanced technologies from Donaldson filters include such industry leaders as Endurance(TM), PowerCore(R), Duramax(R), Synteq(TM) and Ultra-Web(TM). Donaldson filters are used in the over-the-road classifications up to and exceeding 33,000 GVW, off-road equipment such as construction and agriculture, plus industrial applications.

Alan Amatuzio, Executive VP and COO of AMSOIL, said, "The market potential is very exciting. The addition of Donaldson Heavy Duty Filters complements our line of premium synthetic heavy-duty lubricants perfectly. This combination is a very good fit for our customers and our dealers."

Donaldson filters are now available through all AMSOIL distribution channels which include over 80,000 dealers world wide.

About Donaldson Company, Inc.

Donaldson Company, Inc. is a leading worldwide provider of filtration systems and replacement parts. Founded in 1915, Donaldson is a technology-driven company committed to satisfying customer needs for filtration solutions through innovative research and development. Donaldson serves customers in the industrial and engine markets including in-plant air cleaning, compressed air and gas purification, power generation, disk drive and microelectronics filtration, off-road equipment and trucks. Our 10,000 employees contribute to the company's success at over 30 manufacturing locations around the world. Donaldson is a member of the S&P MidCap 400 Index and Donaldson shares are traded on the New York Stock Exchange under the symbol DCI. Additional company information is available at www.donaldson.com.

About AMSOIL INC.

AMSOIL INC. is "The First in Synthetics"(R) and the largest independent manufacturer and recognized leader in synthetic lubrication since 1972. AMSOIL products are distributed throughout the United States, Canada, Puerto Rico, New Zealand and in 26 countries worldwide. For more information about AMSOIL synthetic lubricants and performance products visit www.amsoil.com or call AMSOIL at (715) 392-7101 or 1-800-777-8491. AMSOIL INC., AMSOIL Building, Superior, WI 54880.