Air compressor oils, do they make a difference?

[thejunkmanadv]

I recently upgraded my air compressor and after break in I wanted to change my oil out for a full synthetic, but do they really make a difference?

I decided to do some rudimentary testing on my own. I made a 5 minute video about it, see it here.

I choose Royal Purple's Recip 100, it had the most reviews on amazon and a very positive rating overall.

For those that get pissy about clicking a link to a youtube video. For the TLDW (too long, didn't watch)

My testing didn't show that it ran cooler or quieter, but it did sound different as evidenced by the spectrogram (as seen in the video).

My method seems pretty straightforward, but maybe I missed something. Let me have it, it is the internet I know you will.

 

[ImportTuner]

Interesting ... Thanks for sharing

 

[Milton Shaw]

The difference in temp should be in the crankcase section not the head. The heads temps are from compressing the air that's going to always be the same, not much way oil is going to change the thermodynamics of compressing air. The lub qualities of syn. oil should show up in lower crankcase temps and bearing noise from the lower end, which is not where most of the noise is coming from. It might show up in lower amp pull on the motor but we are probably talking factions of an amp difference. Like syn oil in cars will effect the gas mileage but too many other things will also effect it, such as tire pressure, wind speed and direction, temp, load,and driving habits to really be able to show a percent change.

 

[thejunkmanadv]

Well the head temp I didn't expect a change obviously, but the cylinder is where I "wanted" to see change as that is where some (most?) of the friction would be.

 

[TractorJeff]

All I can say is that my REAL 2hp Compressor will start in Winter time with Synthetic but not Regular Compressor Oil!

 

[exranger06]

All I can say is that my REAL 2hp Compressor will start in Winter time with Synthetic but not Regular Compressor Oil!

Me too. I have a little 4 gallon Campbell Hausfeld compressor that's oil lubricated. It came with a little bottle of oil, which I believe was a SAE 30 non-detergent oil. The compressor often would not start at all in the winter and would trip the breaker. After the break-in period, I changed the oil to Mobil 1 5w30 (which is actually recommended in the manual) and never had a problem with it starting in the winter again.

 

[xjfish]

Thanks for posting.

Do you have any opinions on using (synthetic) ATF? As far as i know its considered about a 10w hydraulic oil. I am currently using this on a new pump mostly for break in because its what I had laying around... 10W is about the lowest viscosity recommended on said pump. I think it will work much better in cold temps vs. SAE 30 but I plan to switch out to whatever is best for longevity.

 

[thejunkmanadv]

All I can say is that my REAL 2hp Compressor will start in Winter time with Synthetic but not Regular Compressor Oil!

This compressor (the one in the video) is a 3.7hp 230v, but yeah I have experienced the same thing with my small portable 2hp (120v) compressor too.

 

[thejunkmanadv]

Thanks for posting.

Do you have any opinions on using (synthetic) ATF? As far as i know its considered about a 10w hydraulic oil. I am currently using this on a new pump mostly for break in because its what I had laying around... 10W is about the lowest viscosity recommended on said pump. I think it will work much better in cold temps vs. SAE 30 but I plan to switch out to whatever is best for longevity.

I am no expert, but ATF is rated more like a gear oil I thought. However I wouldn't think there would be any harm in using it. Its design characteristics seem like it would be a worthy choice, (anti-foam, high heat tolerance, extreme pressure, corrosion resistance). I use synthetic ATF oil in my separate sump motorcycle gearboxes, except for the ones that share lubrication with the engine oil obviously.

My understanding is air compressor oils have their own standards or ratings for the viscosity and they are not a 1:1 correlation to the SAE standards we might be accustom to.

 

[Bretny]

Get the right oil. Its cheap to buy the good stuff and a prety expensive piece to replace when it goes bad.


I use amsoil iso100 or what ever the stuff is called. Got half a case many years ago so should last me a lifetime.

 

[James E]

Well the head temp I didn't expect a change obviously, but the cylinder is where I "wanted" to see change as that is where some (most?) of the friction would be.

Actually, I would have expected there to be a difference in the head, too. Since, like you, I figured that's the biggest friction surface and the metal is thinner there. Maybe the compressed air generates so much more heat than the rings against the cylinders that you just can't measure the frictional difference there?

How about measuring the temperature of the oil itself after you run it for a defined period of time?

 

[thejunkmanadv]

Actually, I would have expected there to be a difference in the head, too. Since, like you, I figured that's the biggest friction surface and the metal is thinner there. Maybe the compressed air generates so much more heat than the rings against the cylinders that you just can't measure the frictional difference there?

How about measuring the temperature of the oil itself after you run it for a defined period of time?

After posting this and making the video I am kicking myself for not putting a probe in the oil. It would have been easy enough to do, but I guess my thought at the time was heat transfer to the cylinder should be a good measure. If significant change higher or lower, then a debate could be had about the heat transfer properties of the oil itself.

I am hoping some people will comment on the video suggesting maybe other ways to tackle this testing.