On oil cleanliness and machinery longevity

[4IsWEm]

Here goes:

I have an air conditioner that I use to heat my home during wintertime. I have been using it for the past 8 years. It's total electric energy consumption during each winter has been ~2500 kwh. This equates to ~2300 hours of operation per winter, a total of 18400 total hours of operation.

I should have to add the summer operating hours, ~3000.

Overall operating hours should be ~21400 hours. That's many many hours if you ask me.

There are 3 facts about an air conditioner:
1) Oil is practically never changed (I have never changed the oil in an AC)
2) The quantity of oil is very small
3) Oil contamination (chemical or particle-wise) is very small since they are closed systems.

It is very easy to conclude that the greatest part of wear in other machinery is due to contamination, given that the machine is well designed in the first place and loaded within its limits.

The usefulness of bypass filtration in car engines just went up a couple of notches in my mind.

I would like to hear your thoughts on the above. Thanks

 

[951Indy]

I suspect AC's, like internal combustion engines, don't experience most failures because of oil cleanliness.

My experience suggests most cars that need a new engine are from being overheated, timing belt failure, and oil starvation. These events probably account for more cars hitting the salvage yard than worn bearings from using a OCOD.

 

[bullwinkle]

A/C compressors in a sealed system operate in an oxygen-free environment, so the oil will pretty much last until the compressor motor burns out or suffers a mechanical failure. Keeping your coils clean is the best way to ensure a long life.

 

[Quest]

Originally Posted By: alexeft
Here goes:

I have an air conditioner that I use to heat my home during wintertime. I have been using it for the past 8 years. It's total electric energy consumption during each winter has been ~2500 kwh. This equates to ~2300 hours of operation per winter, a total of 18400 total hours of operation.

I should have to add the summer operating hours, ~3000.

Overall operating hours should be ~21400 hours. That's many many hours if you ask me.

There are 3 facts about an air conditioner:
1) Oil is practically never changed (I have never changed the oil in an AC)
2) The quantity of oil is very small
3) Oil contamination (chemical or particle-wise) is very small since they are closed systems.

It is very easy to conclude that the greatest part of wear in other machinery is due to contamination, given that the machine is well designed in the first place and loaded within its limits.

The usefulness of bypass filtration in car engines just went up a couple of notches in my mind.

I would like to hear your thoughts on the above. Thanks



Just like your refrigerators: you typically don't tackle compressor oil changes inside your AC system once it's sealed.

Just leave it alone and let it run til it dies. Chances are: other components such as blower fan motor, controller board, etc. dies before your compressor dies due to lubricant issues.

Q.

 

[4IsWEm]

Thanks for the advice guys, but what I am trying to do is to contrast the example of the AC with a car engine, highlighting how clean oil and a sealed system help in longevity.

I will certainly not be changing the oil of the AC.

 

[MolaKule]

1. Oil in an IC is not an isolated system. Air and fuel are drawn in from external sources which oxidizes the oil. Extreme heat polymerizes the oil and beats up the additives.

2. In an A/C, a high stability POE base oil and an AW package is sealed so no oxidation occurs.

3. So there is more than just filtering for comparison.

A well filtered oil can extend oil life a bit and it can reduce wear a small amount, depending on the filter's ability to trap a majority of wear-size particles.

This where by-pass filters can show a slight advantage over full-flow filters.

 

[dnewton3]

What keeps an ICE running long is clean oil. How you get there is one of two roads:
- frequent OCIs
- superior filtration

However, you also have to keep in mind the other contributors to wear reduction in ICEs. Outside contamination that enters via the air and not the oil, and the large effect that oxidation has in a positive manner. Yes - some amount of oxidation is a good thing, believe it or not. This is what encourages and contributes to the anti-wear tribochemical barrier being established. In fact, if you simply establish a modicum of reasonable filtration (air and oil) then the anti-wear layers are what really help control wear. Purchase and read SAE 2007-01-4133; it's quite revealing.

The one contaminant that is a byproduct, rather than directly ingested, is soot. And it is quite abrasive. However, it also starts out quite small; sub-micron in size. If the anti-agglomerate package is healthy, the soot will stay small, and be of little consequence to the wear rates. Only when it becomes larger (5um and up) do you really need to worry about wear rates being significantly effected. This is a case of pebbles and boulders. One particle of soot 10um in size floating about is very critical. But 10 individual 1um particles are meaningless. The total soot count is the same by percent weight, but the size makes all the difference. And it is the oil add-pack that controls these issues. Until the add-pack is compromised, the soot means little. This is why frequent OCIs can have the same effect as superior filtration.

A clean sump is a desirable sump; how you get there is up to you. You can either filter or flush out contamination. Therefore, life cycle is a matter of clean lube, not premium filters. The difference being between clean lube is a result; filters and flushing are methods to achieve such a result. A clean sump is NOT exclusive to superior filtration.

Bypass filters are a means to greatly extending the OCI; they are a fiscal tool, and nothing more.