Machine breakdowns are among the biggest production issues that miningcompanys face. These breakdowns, which are often due to contaminated hydraulic fluid, are expensive, both in terms of repair costs and downtime. This may lead to the minecompany concluding that it needs to change its oil regularly. Of course, this is costly as well as environmentally unsustainable. It also is not always effective, as contaminants is still left in the system when the oil is draint and new contamination may enter the system