Air Compressor Oil: Will Engine Oil Do, and Which Grade Fits?

The manual says SAE 30, the shelf holds engine oil, or the compressor oil has turned milky? Unless the manual says otherwise, use a non-detergent compressor oil in the grade it gives.

The Other Oil range at PartsForMachines lists 14 compressor oils for piston, screw and vane compressors, from ISO 46 to ISO 150, in 20-litre packs and 208- or 209-litre drums.

Can I Use Engine Oil in My Air Compressor?

Only if your compressor’s manual allows it; otherwise, use a non-detergent compressor oil. Piston compressor manuals usually ask for oil without detergents, and some warn that detergent or automotive oil can cause pump problems.

Compressor oils are made for the job and tested for how quickly they shed water. Brand matters less than type, grade and class: manuals often name a type and grade rather than a brand, such as a non-detergent SAE 30 compressor oil.

My Manual Says SAE 30 or SAE 40: Which ISO Grade Do I Buy?

Convert it: SAE 30 is about ISO 100 and SAE 40 about ISO 150, so buy a compressor oil in that ISO grade. An ISO number gives thickness only, so an oil marked ISO 68 is right only if it is a non-detergent compressor oil that meets any class your manual names.

For an SAE 40 manual, the Shell Corena S2 P 150 (550065677) is a mineral ISO 150 oil for piston compressors. Where the manual asks for ISO 68, a mineral piston oil such as the S2 P 68 (550026293) fits. For other grades, such as 20W-20, send our team a photo of the manual page.

Why Has My Compressor Oil Gone Milky or Sludgy?

Water has got into it, usually from humid air condensing inside the pump; creamy, milky or sludgy oil all point to moisture. It is more likely in damp workshops and on compressors that only run in short bursts. The pump may not get hot enough to drive the moisture out.

Change the oil straight away: oil with condensed water in it does not lubricate properly, and running parts can wear early. Then tackle the cause: run the compressor for longer spells, for example a full hour every week. Also make sure the pump holds non-detergent compressor oil.

How Often Should I Change Compressor Oil, and Is Synthetic Worth It?

Change it at the interval in your manual, in months or running hours, whichever comes first. For mineral oil in piston compressors, makers’ figures run from about 200 to 500 hours, or roughly every three months, and sooner with heavy use. Mineral compressor oil in the right grade is fine if you keep to that.

Synthetic is worth it if the manual approves it and you want fewer changes. Synthetic oils run longer between changes: one maker allows 12 months or 2,000 hours, against three months or 500 hours for mineral. For an ISO 100 (SAE 30) manual that approves synthetic, the synthetic ester S4 P 100 (550027265) is one example.

What Should I Check Before I Buy Compressor Oil?

• the oil grade in your manual, SAE or ISO, converted to an ISO grade
• your compressor type: piston, or rotary screw or vane
• any class the manual names, such as DIN 51506 VDL or ISO 6743-3 DAA
• mineral or synthetic, and whether the manual approves synthetic
• the pack size: 20 litres for one machine, a drum for several

Browse the Other Oil range, or contact the PartsForMachines team by WhatsApp, telephone or email with your compressor’s make, model and the oil grade in its manual.

Pack sizes, delivery options and returns terms are shown on each product page. A 30-day return policy applies to eligible items.

Frequently Asked Questions

Is air tool oil the same as compressor oil?

No. Air tool oil is dripped into a tool’s air inlet, or fed through an inline lubricator, to lubricate its air motor. Compressor oil fills the compressor pump’s crankcase. Use the oil each maker names for each job.

Do I need the compressor maker’s own-brand oil?

Not usually. If the manual specifies a type and grade rather than its own oil, any compressor oil meeting both will do. While the compressor is under warranty, check its terms before using a different oil.

My manual names DIN 51506 or ISO 6743-3: what do I look for?

Look for an oil that lists the same class. Both are compressor-oil classes: the S2 P 68, for example, meets DIN 51506 VBL and ISO 6743-3 DAA (normal duty), while the S4 P 100 meets VDL and DAB.

Does a screw or vane compressor need a different oil from a piston one?

Usually. Rotary screw and vane compressors take oils made for rotary service, such as the synthetic S4 R 46 drum (550026202). Shell rates it for 10,000-hour oil changes, or up to 12,000 hours in some conditions.

Can one oil cover both my piston and my screw compressor?

Sometimes. The Q8 Schubert 46 20-litre compressor oil is made for piston, rotary screw and vane compressors, and for vacuum pumps. One oil can then serve a mixed workshop, provided each manual accepts ISO 46 and the oil’s classes.

Do I need a different compressor oil grade in winter or summer?

Sometimes. The recommended grade can vary with the temperature around the compressor. One maker’s chart, for example, gives ISO 32 below 4°C, ISO 100 (SAE 30) from 4 to 27°C and ISO 150 (SAE 40) above that. Follow your own manual’s chart.

Can I use a synthetic 10W-30 instead of straight SAE 30?

Only if your manual lists it. A manual may approve a synthetic 10W-30 as an alternative to non-detergent SAE 30 compressor oil, or name a single-grade compressor oil only. If yours gives one grade, stick to it.

Should I buy a 20-litre pack or a drum?

It depends how many compressors you run. A 20-litre pack suits one machine or a small workshop; a 208- or 209-litre drum, dispensed with a workshop pump, suits a workshop running several compressors, or a fleet. Keep opened packs sealed in a clean, dry place.