Jump to content
I Forge Iron

cold start compressor

Recommended Posts

Any advise for helping a shop air compressor start on cold days ?
I run 30 W compressor duty oil in the crankcase and change it about every 6 months. Should I switch to a multigrade like 10-30 W motor oil ? Is that a bad idea for this application ? I think the compressor duty oil has an anti foaming agent.
The compressor in question is a 60's vintage Worthington 2 stage with a 3 hp. 1725 rpm 220 V motor on it. I think it was originally equipped with a 5 hp. motor but the 3 hp. gives me enough air power for my needs. The slower RPM keeps the noise level down. Would a bigger motor help on cold starts ? or make it worse ? The compressor is on a dedicated 30 amp 220 volt circuit breaker which I also use for the on/off switch. The run from the panel is 30' of #10 wire
The compressor is outside under cover. When I say cold weather, out here it seldom gets below 20 F and then not for long.
I also find that if I drain the air out of the tanks and lines it helps with the cold starts as the motor is not having to start against a load . This is probably a good idea anyway for minimizing moisture and ice in the lines.

Link to comment
Share on other sites


The compressor that most resembles what you are talking about is at my inlaws, we solved the problem by using heat tape like you would install on water pipes. We have wound this around the compressor jug and casing and it keeps everything warm enough to allow good operation. Note you really need to leave it plugged in 24/7...


Link to comment
Share on other sites

Many industrial duty compressors use a case heater, an electric heater to keep the oil at proper operating temp for starteing. Also an unloader vale is almost a requirement in the bigger compressors.
Compressor oil is VERY different from engine oil. There are 4 basic types.

1. Turbine oil. This is a straight petroleum oil, additized for compressor duty. Good in industrial practice for about 1000 hours.

2. PAO oil. This is similar to Mobil1. The PAO stands for polyalphaolefin. This is a much better oil for compressors than the turbine oil. Should last 2000 hours and one brand is Syn-flo. These seperate out the water better, and reduce oil bypass in many cases.

3. Polyglycol. These are a real step up. Last for about 5000 to 6000 hours, and are more environmentally friendly when the condensate goes into the sewer.

4. Silicon oil. This is the top of the line. Lasts beyond any measure I know.

All the above hours ETC are based on industrial screw compressors used in continous duty. The cost is basicly doubled in each step up the ladder. In an older piston compressor, in home shop use, I would probably go for the turbine oil, and change often. I would look over the oil for any "Creamyness" indicating water content. Change at the first sign of water.
Good luck.

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

  • Create New...