Indiana-based Calumet Specialist Products LP is set to buy Royal Purple.
The acquisition will boost Calumet's lubricants portfolio by taking on privately-owned Royal Purple's high performance lubes business which covers a range of sectors from automotive, industrial, marine and motorsport.
The deal is worth around $335m and will be paid in cash and through borrowings. Based in Houston, Texas, Royal Purple is expected to become part of the Calumet family in July 2012 and is one of a number of acquisitions made by Calumet since January.
Calumet itself produces lubes, solvents, waxes and asphalt and has a market capitalisation of around $1.25bn.