Air compressors, cold weather, oil choices.

[TemporaryKubotaOwnerMark]

Weather has been normal lately, meaning cold. Today it's about 40 outside, and my compressor is struggling. Slow to start up, and gains some speed as it runs, but still not running as fast as it should. I shut it down so I don't burn up the motor.

This is an old Sanborn 2 cylinder 5 horse on a 60 gallon tank. Standard oil bath type compressor, like this one. In fact, it is that one. The old one seized up about a year ago and I replaced it with the HF unit. So far so good, but...

There's this cold weather issue.

I have read forever that you can't use regular automotive oil in a compressor. Has to be straight weight 30 non-detergent, and I have never understood why. I would think some 5w40 synthetic would solve my cold weather problem and extend the life of my compressor.

So, what's the reason, or is this an old wives tale? Or is it a relic from the past which lives on past its useful life?

 

[Zerk]

I have been using synthetic air compressor oil, never noticed any issues. I have ran colder then 40F. Not sure best weights, I just bought the syn air comp branded oil in the air compressor aisle.

I think years ago, you used SAE. At work we use syn oil, for air compressors at unmade locations, thought they have small heaters in comparments, for condensation mostly.

 

[George2615]

I use non detergent SAE 20 weight in my compressor. In winter, the area in the garage by the compressor only gets down to about 40* F. and I don't have a problem.
Amzoil, Quincy, Mobil, Dewalt and many other companies do sell 10 or 20 weight non detergent synthetic compressor oil. There is also Synthetic blend as well as non synthetic 10 or 20 non detergent.

 

[tcreeley]

I often ran my compressor for my nailing gun when I was building the barn when it was below freezing. The secret for me was a good electric supply line. Too small a gauge and it would trip. The other thing was a magnetic heater to warm the oil. After the first start it was ok.

 

[Stimw]

The reason for NON Detergent oil is compressor sumps attract moisture and regular oil will mix the water and oil and you end up with the pudding/milkshake mix.
With Non D the water and oil stay separate.
You might find a Synthetic Compressor oil for it. Since you only need less than a qt. buy the good stuff.

 

[Soundguy]

CH makes a synthetic compressor oil.

My huskie compressor also said i could use 5-10w20-30 synthetic engine oil.

I ended up running the syn compressor oil.

I have a much older ( 20ys) chinese pancake compressor I have 10w30 WalMart syn oil in.. Both are fine

 

[oldballs]

I had the same issue as the OP. Working in an unheated garage, it can stay down to 20 deg F, in which case the 4.5 HP (26 gallon) belt drive compressor just barely turns over with the OE recommended 40W non-detergent oil. So I put 10W non-detergent in as was recommended in the OE manual. But now this crazy weather goes from 20 deg to 65 deg and the 10W needs to come out. Geeze........ I need something in between that'll work year 'round in this climate.
Cheers,
Mike

 

[Zerk]

Not my area of expertise. But sometimes wonder if overly worried about oil choice for this application. I change mine, but I also wonder how it wears, without gas getting mixed. We are protection a piston and bearing, that are not moving at RPMs of gas engine.

I follow recommondations, but for our small air compressors, with limited use, I dunno. Hard starts, would worry more about bearing protection, then proper viscosity But I am speaking from my bowels on this.

They sell syn oil marketed for air compressors. For the small amount my little machine uses, I use it.


I have two compressors in cold barns, and another in insulated garage. The insulated one is ran upper 30s or low 40s. Barn ones closer to zero at times. I don't run mine enough to know life.

 

[ray66v]

Have you checked the belt? They will slip when it's cold, but run fine when it's warm.

You are "supposed" to flush an older compressor when switching to synthetic. Then, they only appear sell compressor flush in 5 gallon pails, so you can't do it.

At this point, many have switched without flushing. If there was an issue, it would have showed up.

Lubriplate makes high quality compressor oil, in 10, 20, 30, and 40W.

I'm running Lubriplate AC series 20W mineral oil, in my 30+ year old compressor.

 

[FTG-05]

The reason for NON Detergent oil is compressor sumps attract moisture and regular oil will mix the water and oil and you end up with the pudding/milkshake mix.
With Non D the water and oil stay separate.
You might find a Synthetic Compressor oil for it. Since you only need less than a qt. buy the good stuff.

I came here to ask that very question. Seemed like a no brainer to me: just use whatever you use in your tractor or truck or car or whatever.

Learn something new every day. Thanks!