How long can a mineral lube oil last? Is it 30 years at 30C & 15 years at 45C? Synthetic oil life is longer?

You mean at the stockroom shelf?

We use a Shell Ondina Mineral Oil at our plant and the supplier recommends storage in less than 50C. But I did not get an expiration date or shelf life period.

Any way, our turnaround for this item is not long. I really doubt a container of this oil sits on our stockroom shelf more than six months. On the other hand, we have a good supplier, so we only keep one container in use and one in storage.

This message has been edited. Last edited by: Eugene,

Storeage is extremely important. I can't count the number of times I have see 45 gallon drums stood upright outside with the lids full of water. For reference, if you MUST keep them outside, chock them on their sides, with both the filler and vent caps below the level of the oil. Obviously this only works when the drums are a bit more than half full.

The test for the lube oil life was supposedly done at service conditions, not at storage conditions acc to my friend. The test was said to be done by BHRA (British Hydromechanics Research Association). Anybody can get this paper? I tried to search Internet but unfruitful.

This message has been edited. Last edited by: Josh,

Some test for remaining life may include Turbine Oil Stability Test (TOST) and Rotating Pressure Vessel Oxidation Test).

Also in later stages acid number and viscosity. The transformer people use I.F.T. as an earlier indication of oil aging than acid number and I'm not sure why rotating equipment people don't use it for this purpose.

Of course interolerable levels of contaminants may also render oil unuseable.

I think you may be able to check gain some insight to remaining concentrations of original additives with certain tests but I'm not sure.

I haven't heard many thumbrules for setting lifetimes. Mostly it depends on experience from your application. Temperature would be a big factor as you specified and also air, moisture, other types of contaminants, filtration etc.

Do the TOST & RPVOT quantify the remaining life eg years?

A range is given to each TAN & viscosity. Once we reach the upper range, can we quantify the remaining life or we just know the end life is coming soon?

To roll together your questions: TOST/RPVOT would be earliest indication to forecast aging, acid number a later indication and viscosity the latest indication.

If you reach your limit on viscosity (for example 10% change), and the cause is not contamination or sample error, your oil is in sad shape and should have already been changed imho.

Acid number is trickier and acts different for different oils and also sensitive to contaminants. In general I tend to think when you reach the limit it's time to plan an oil change.

RPVOT and TOST should change fairly linearly with aging assuming relatively stable temperature and oxygen (unlike the others which may not show any change early). So you should be able to draw a line to forecast when you will reach the limit. One limit would be 25% of new oil RPVOT. In general would like to plan to change at the time you reach that limit although I think the 25% means you still have 25% of the "life" left.

I'm not sure there are any hard and fast rules in this area. If your sump is very large the costs can be large and you may examine the situation closely to see if you are comfortable extending the interval. If your system feeds hydraulic controls for a large machine, your probably want to be very conservative because it doesn't take much oxidation products to screw things up. If only bearings and no likely places for clogging, you might under some circumstances be willing to accept the fact that you will have some increased tendency for oil decomposition products to form and acidic byproducts to attack your metals... longer-term issues.

Any lube oil has the property that it will loose its property w.r.t.time as it is being prepared by using chemicals.any molecule starts oxidation after certain time period,or starts evaporation,hence no lube oil has the life more than 5 years.

quote:

Originally posted by Eugene:
You mean at the stockroom shelf?

We use a Shell Ondina Mineral Oil at our plant and the supplier recommends storage in less than 50C. But I did not get an expiration date or shelf life period.

Any way, our turnaround for this item is not long. I really doubt a container of this oil sits on our stockroom shelf more than six months. On the other hand, we have a good supplier, so we only keep one container in use and one in storage.

No lube oil has a life more than 5 years? Can I quote this statement openly? Is it published anywhere? I thought some people still believe in 6 monthly lube oil change for small machineries with small volumes of lube oil. P/s Sori if this sounds a bit probing but it's a way to keep this forum going. Don't be put off by it esp'ly new members. I guess everybody just wants to know the truth.

This message has been edited. Last edited by: Josh,

If you look at the OEM recommended shelf life for oils and greases it can vary widely, from as short as one year to 10 years or longer. There are various reasons for the shelf lives: routine formula changes every few years accumulating to make the oil very different after several small formula changes, additive packages settling or plating out, normal oxidation, unknown storage conditions, etc.
A 4 to 5 year shelf life with good storage conditions (temperature controlled (10 to 40 C) and out of the weather) is a pretty good standard. Of course individual situations vary and if doubts exist about the 'new' oil quality I would recommend testing the oil prior to use

If the last use and testing is perform in May 2006; for how long you consider the obtained values valid?

The life depends much on the storage conditions, for instance the "practical limit" for diesel fuel is 6 months, because of the aging process.

Like a friend of mine found out at the wrong time.

I had to tow him back to town on a rainy sunday afternoon. He had filled his tank with diesel from a barrel standing one year in his yard, before he left camping

Since there are hydrocarbons also in lubricants , I would be very cautious if it is older than two years. Especially if the vendor cannot proof it (you know the ISO etc.. stuff)