Air Compressor Oil

[George Vaughan]

Everything I can find regarding air compressor oil recommends non-detergent. What would be the harm in using a high detergent formulation? Just curious. Thanks

[Jim Conte]

The detergent actually burns under compression. Not a problem in an engine where there is combustion anyway, but it will carbon the valves, build up deposits on the head and piston, and generally put carbon and debris through the rings.

If you wanted to do an in-service clean up of a compressor crankcase, running detergent oil for a few 8 hour days probably would help, but it should be drained hot after a run, so the gunk gets washed out.

I heard a sea story about a chief machinist's mate who tried cleaning an air compressor by dribbling diesel fuel down the air intake. They ended up scraping him off the overhead with a putty knife.

[Andrew Mackey]

Detergent oils will loosen any varnish in the crankcase interior, allowing it to get into the main bearings and the conrod lournal. Compressor oil has extra componants that lesson friction, that are not available in motor oils. If you have to use motor oil, use non detergent, and replace with a compressor specific oil as soon as possible.
Andrew

[ronm]

I was working in a farm shop one day, & the compressor was having a hell of a time making air, took forever to build up, but the line from the comp. to the unloader valve was getting so hot it was smoking....finally stopped what I was doing & pulled the unloader apart-it was completely plugged with carbon-looking crud...burned detergent. They had been using motor oil in the comp. for years...cleaned it out, & the pump actually made air-it was worn out, but at least it wasn't deadheaded against the unloader....

[K D Redd]

Most pumps SPEC. a DIN 100 compressor oil BUT I installed a new Campbell-Hausfeld for our fire department. In the info for the compressor, the listed the DIN 100 oil which I think is a 30W BUT they listed a second choice of MOBILE ONE 10W-30. I have two Devilbiss pumps that spec-ed a 20W-20 oil when I bought them new. I was running Pennzoil 20W-20 which was getting difficult to find. I changed them to Mobile ONE 10W-30 and saw lees oil consumption than the 20W-20. They also start easier in the winter. They have been in service since about 1988 and seem to work as well now as when new. All of these pumps are single stage twins.

Kent

[Craig A]

Some years ago we sold a fairly expensive 2 stage compressor (from W. W. Grainger) and the instructions specified DETERGENT oil. I CALLED the company to verify their information as everything else I had ever seen specified NON-detergent oils. I was assured their information was correct.
Less than a month later our customer brought back the compressor and it was junk.......

Another call to Chicago: "The oil recommendation was a misprint".......

They sent a new compressor.......no questions asked.......

[Gary Pflum]

This may or may not open up an oil can of worms but here goes. In a nut shell, Non detergent oils allow the particles and unwanted material to settle in the bottom of the crankcase on engines or equipment that do not have a filtration system. (filter)
Detergent oils hold the particles in the oil so it can pass through the filter system.
Many people did not want to trust or change to the new oils when they were introduced. They thought the oils would clean the engines so fast that it would ruin them. In some cases the oils did just that. If an engine has a non filter system it needs the particles to land in the oil pan and stay there. When the detergent oils are put in a non detergent engine it would pick up the dirt, suspend them in the oil and keep recirculating them. Thus hurting the engine.
Non detergent oil in a filtered engine is fine however you will end up with sludge and dirt in the oil pan as well as in the filter.

[Craig A]

Would this thread be better in the Shop Talk forum?

[ronm]

Sounds like shop talk to me, Craig...you're the doctor...

[smgussey]

Both of my single-stage twin pumps (one cast iron, the other aluminum with cast iron liners) spec 10w-30 synthetic oil ONLY.

I've been using 10w-30 oils in compressors for around 20 years now and have never had a problem. Dad's compressor is about 18 years old now, and he has another that is around 10 years old. Mine are about 8 and 3 years old.

[MoRo]

Since air compressors have oil changes so infrequently, I can understand the suspended particles, caused by detergent oil, being a problem. What if, detergent oil was used and changed regularly, just like in a small engine. Your 21" push mower doesn't have an oil filtering system, and the recommended service interval is something like 25 hrs of operation? If the oil were to be drained hot, the suspended gunk should flow out with the draining oil.
Am I more full of hot air than usual?