What oil do I put in a compressor?

After constantly getting fed up with my 24l (Oil Free) compressor
running out of air, I have upgraded to a 100L model. But this one needs
oil!
The oil level is a little low in the window and I would like to top it
up, so what oil do I use? Can I use standard 4-stroke motor oil, or do
I need something special?
What about mixing? If I don't know whats already in there, is it 'safe'
to just top it up or should I drain it first?
Any info would be appreciated
Jon
Reply to
jon.p.weaver
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Here in the US, they sell oil that is purposely made as "compressor oil", that's what I would put.
i
Reply to
Ignoramus28190
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Reply to
Don Foreman
Interesting.. I will see what I can find in the UK.. It appears that they are all synthetic, and rather than take the risk of 'mixing' oils, I am tempted to drain mine and add all new oil
Many thanks for the info
Jon
Reply to
jon.p.weaver
You can use motor oil but it must be non detergent type.
Gary Pewitt N9ZSV Sturgeon's Law "Ninety per cent of everything is crap"
Reply to
Gary Pewitt
Is it a standard piston compressor with a splash-lube crankcase, or pressure lube? Who made it? Model number? How many stages and how many cylinders?
If you can't find a data plate and don't know who made it, put pictures of the unit up on a webpage somewhere and point us to them with a link here. Someone (probably in the European contingent) will recognize the maker, and can give you clues as to where to get the definitive maintenance information.
You usually use a non-detergent oil in an air compressor, and the additive package is significantly different from regular gasoline (petrol) or diesel engine oils - but they will work. Some makers specify a synthetic lubricant in their two-stage units because they run very hot at maximum pressure.
Do NOT mix new and old oils if you have no idea what's in there now - even if it's a bit low there is oil in there. The odds are very low IMHO, but if they've got some odd oil in there you could have a reaction in the crankcase between the new and old oils, and gelled goop doesn't lubricate the bearings at all.
If it's a screw compressor (Roots Blower - usually 25 HP or better) they require a totally different type of lubricant, and instead of a regular air receiver they have a pressurized oil separation and lubricant supply tank in the air output that recirculates the oil.
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Reply to
Bruce L. Bergman
As others have said, non-detergent.
My C-H calls for IS068 which is the same thing as non-detergent SAE20.
JW
Reply to
jw
The compressor is made by 'Valley', buts its just a cheap, rebadged generic compressor made in China..
Its an upright, 3hp, single piston type with a very similar 'engine' to my old Oil Free 24L version (again, a cheap, rebadged import).
I think that I will drain the old oil out and put in some new stuff... I found in the (limited) instructions that it suggest N32 oil in the winter and N68 in the summer.. I guess this "ISO" number.
One questions about oil changes is, how do I get all of the old oil out? Obviously I heat it up, open the drain plug and tip it out, but do I have to get EVERY drop out? Does it matter if there is still a little bit left over?
I think I know where I can get the right oil in the UK, so am going to change whats in there, just in case.
All the best
Jon
Reply to
jon.p.weaver
stuff...
Jon,
If you are worried about reaction between existing oil and new oil then you will have to empty, then flush with new then empty several times to be sure none of the old oil is left behind.
As it is a generic Chinese machine I would just go to your local Machinemart and buy a bottle of their compressor oil and top it up.
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AWEM
Reply to
Andrew Mawson
Yes - sounds like regular SAE20 - ISO68 non-detergent petroleum based will do just fine. It isn't one of the fancy types. And if you don't operate it regularly in sub-freezing cold areas, you don't need to worry about putting ISO32 "winter oil" in.
Do not worry about that - I mentioned it on the off chance this unit was something exotic bought as surplus that used an exotic oil.
When you do the first oil change (after you wipe up the mess as the oil flows down the side of the unit...) is the time to add a pipe nipple and any elbows needed to get the oil drain to a convenient spot for the catch bucket. Make future oil changes neater.
But if you put a ball valve in the oil drain line, be sure to put the pipe plug back in the end, too - there are gremlins that turn valve handles. (2-year olds, cats, piles of junk falling over...)
It's like a car engine - they want you to run it for an hour unloaded (with the air output line unplugged, no pressure in the tank) for ring seating, then you change the oil after 5 to 10 hours to get rid of the initial manufacturing sporge in the compressor crankcase, then every 50 hours.
Do you have an hourmeter wired across the motor yet? Cheap way to remind yourself to change the compressor oil once in a while.
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Reply to
Bruce L. Bergman
Compressor oils are BS. I bought a 2 stage 5 HP cast iron compressor new in 1975. Let me say it runs over 5 hrs a day (due to my CNC machines needing so much air). Every 3-4 years I have to change the valve plate. When I do the hone marks are still on the cylinders.
What oil do I use 10-30 motor oil, same as you put in your car. I change it once a yr & at 5 hrs running 6 days a week that's a lot of use. So it's now 30 yrs old & still running fine.
Reply to
Why
The only problemis that Machinemart only do SAE40, which is ISO100 in 1 litre sizes.. If I want 30 (ISO68), I have to get 5litres which may be a bit of an overkil.
I have found another place which does 30 in 1 litres bottles, so will get some of that.
Still a little concerned as to whether I should just 'top it up' or go a complete change!!
Why do I worry about everything? :)
Jon
Reply to
jon.p.weaver
Like some others have said, straight weight 20 or 30, non - detergent.
Reply to
tomcas
That makes sense , but after 30 years running I can't tell any wear. And my bores still have the hone marks. Compressors are not like cars where gas contaminates the oil...
Reply to
Why

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