How to make your hydraulic oil last longer

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The price of oil sure is defying gravity at the moment. And unlike previous oil shocks, the experts are telling us the days of cheap oil (and gas) are gone forever. Only time will tell.

But unless you're the owner of a lot of poorly maintained (read: leaky) hydraulic equipment, the price of gas and diesel is likely hurting your wallet more than the price of hydraulic oil. Regardless, you sure don't want to be shelling out for any more of it than you have to.

So this begs the question: how can you make your hydraulic oil go further; last longer? Here's a few pointers to consider:

Keep it in

The first and most obvious thing is to keep it in the hydraulic system. Those couple of slow hydraulic leaks that you've been putting off fixing are costing you more per day, week and month every time the oil price lurches up. There's always been a cost associated with leaks. But the economics of not attending to them is changing rapidly.

Keep it cool

There's a lot of good reasons to maintain appropriate and stable operating temperatures. Oil life extension is not the least of them. According to Arrhenius's Law, for every 10 degrees Celsius increase in temperature, the rate of reaction doubles. The chemical reactions we're concerned with in so far as hydraulic oil life is concerned are oxidation - due to the presence of air; and hydrolysis - due the presence of water. So the hotter the oil, the faster the rate of these reactions - and exponentially so.

By way of illustration, if you pour some cooking oil into a glass, it'll take days, even weeks before it darkens in color - a sign of oxidation. But tip the same amount of cooking oil into a frying pan - which gives the oil a large contact area with air - then heat the begeezez out of it, and the oil will go black in a very short space of time.

Keep it dry

Water too has a number of negative effects on the oil. In so far as oil life is concerned, it can chemically compromise (hydrolyze) the additive package. For example, the antiwear additive ZDDP is prone to instability in the presence of water.

Keep it clean

Unless you've been living in a cave, you know when it comes to hydraulic oil: 'cleanliness is next to Godliness'. But particle contamination also affects oil life. Certain wear metals act as catalysts which increase the rate of oxidation and hydrolysis. Particles can also attach themselves to additives in the oil, resulting in additive depletion when these particles are captured in the hydraulic system's filters.

So to wring the most out of every drop of your hydraulic oil, keep it in; keep it cool; keep it dry and keep it clean. And ONLY change it when base oil degradation or additive depletion demands it be changed.

It's just good maintenance. And good maintenance is good business.

Related articles:

How to deal with water in hydraulic oil
Priority number one in hydraulics maintenance
Hydraulic maintenance lessons from the Qantas mid-air emergency

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