Volume 8, Issue 9 (October 2011)
Compatibility of Vegetable Oil Based Lubricating Greases With Different Mineral Oil Based Greases
Applications of lubricants and greases based on vegetable or animal sources route back to horary past. Until the beginning of the 19th Century, lubricants were reported to be primarily based on beef tallow and vegetable oils. However, advances in petroleum derived mineral oils led to the replacement of these greases with mineral oil based lubricants. The reasons for their dominance may basically be attributed to high performance compared to vegetable oil based lubricants and greases and also their cheaper cost. Environmental consciousness and the speeding race for green lubricants has once again revived vegetable oil based lubricants. Compatibility of greases is an important property of greases that plays a crucial role in some applications like centralized lube system. As the base oil composition of mineral/synthetic oils is significantly different than vegetable oils, it might considerably influence the compatibility of the greases. In view of this, compatibility studies of vegetable oil based greases with mineral oil based greases have been carried out. The vegetable oil based greases formulated with lithium complex, lithium–calcium, and aluminum complex thickeners have been studied to determine the compatibility with non-vegetable oil based greases having lithium, lithium complex, aluminum complex, polyurea, calcium sulfonate thickeners, etc. However, the various greases covered in this paper are just base greases and do not contain any performance additives considering the fact that additives may significantly influence the compatibility of finished grease with other greases under investigation. It is interesting to note that the vegetable oil based greases evaluated so far have either been found incompatible or just borderline compatible.