L-DAB 46 is an ISO VG 46 oil for piston air compressors, not for oil-flooded screw compressors.
- Category: DAB, medium-duty reciprocating and drip-feed rotary vane compressors (ISO 6521-1)
- Viscosity: 41.4 to 50.6 mm²/s at 40 °C
- Screw compressors: need a DAG, DAH or DAJ oil (ISO/TS 6521-2), even at ISO VG 46
- Our L-DAB 46, typical: 45.21 mm²/s, flash point 224 °C, pour point -15 °C
L-DAB 46 is a medium-duty oil for reciprocating (piston) air compressors in viscosity grade ISO VG 46. The code is often searched by people who run rotary screw compressors, and that is where most mistakes happen: a screw compressor that calls for an ISO VG 46 oil needs an oil from a different category, not L-DAB 46.
This guide explains what each part of the code means, how to tell whether your compressor needs L-DAB or a flooded rotary (screw) compressor oil, and what typical data to expect. This page is published by Zhongtian, which makes compressor oils in both categories. Last updated: October 2026.
What does L-DAB 46 mean?
L-DAB 46 means: L for lubricant, D for compressor, A for air compressor, B for the medium-duty reciprocating category, and 46 for ISO VG 46.
- L: the class of lubricants, industrial oils and related products in the ISO 6743 classification system.
- D: family D, compressors. ISO 6743-3 classifies lubricants for air, gas and refrigeration compressors. China’s GB/T 7631.9-2014 is a modified adoption of the same standard, which is why Chinese suppliers use the same codes.
- A: air compressors. All the categories discussed here, DAA, DAB, DAG, DAH and DAJ, are air compressor categories.
- B: the category within the reciprocating group. DAA and DAB lubricants are specified in ISO 6521-1 for reciprocating compressors and drip-feed rotary vane compressors, where oil is injected directly into the cylinders or compression chambers. DAA covers light-duty and DAB medium-duty operation, as refiners such as ORLEN describe their L-DAA and L-DAB grades.
- 46: viscosity grade ISO VG 46, meaning a kinematic viscosity of 41.4 to 50.6 mm²/s at 40 °C.
Can L-DAB 46 be used in a screw compressor?
No. An oil-flooded screw compressor needs a DAG, DAH or DAJ oil, even when its manual asks for ISO VG 46. Compressors that keep the oil in contact with the air throughout compression need a different category. Oils for flooded rotary compressors, both screw and vane, are classified DAG, DAH and DAJ and specified in ISO/TS 6521-2. In these machines the oil circulates continuously with the air, cools and seals the rotors, and is separated out again, so oxidation resistance and water and air release matter more than in a piston compressor.
| Category | Compressor type | Specified in | Zhongtian product |
|---|---|---|---|
| DAA | Reciprocating and drip-feed rotary vane, light duty | ISO 6521-1 | On request |
| DAB | Reciprocating and drip-feed rotary vane, medium duty | ISO 6521-1 | L-DAB medium-load air compressor oil |
| DAG, DAH, DAJ | Flooded (oil-injected) rotary screw and vane | ISO/TS 6521-2 | L-DAG light-duty rotary compressor oil; L-DAJ synthetic screw compressor oil |
ISO VG 46 is a common grade in both groups, which is why the codes get mixed up. The viscosity number tells you how thick the oil is. The letters tell you which compressor design it was formulated and tested for. If your manual names a category, follow it. If it only says “ISO VG 46 compressor oil”, check whether the machine is a piston compressor or an oil-flooded screw before ordering.
Typical data: our L-DAB 46, L-DAG 46 and L-DAJ 46
| Property | L-DAB 46 | L-DAG 46 | L-DAJ 46 (synthetic) |
|---|---|---|---|
| Kinematic viscosity at 40 °C, mm²/s | 45.21 | 45.21 | 44.61 |
| Flash point (open cup), °C | 224 | 224 | 230 |
| Pour point, °C | -15 | -21 | -40 |
| Viscosity index | Not listed | 94 | Not listed |
| Copper corrosion (100 °C, 3 h) | 1b | 1b | 1b |
| Liquid-phase rust test | No rust | No rust | No rust |
These are typical values from normal production as published on our product pages. They are not specification limits; ask for the technical data sheet and a batch certificate with each order.
The full data sheets, including the other viscosity grades, are on the L-DAB, L-DAG and L-DAJ product pages. Our L-DAG is intended for light-duty oil-injected rotary compressors, and the synthetic L-DAJ for single-stage and multi-stage rotary and reciprocating air compressors where a longer service life is needed.
What is L-DAB 46 used for?
L-DAB 46 is used in reciprocating (piston) air compressors under medium load and in drip-feed rotary vane compressors.
- Reciprocating (piston) air compressors, single-stage or multi-stage, running under medium-load conditions, where the manufacturer calls for a DAB oil or an ISO VG 46 piston compressor oil.
- Drip-feed rotary vane compressors, where the oil is fed to the vanes rather than flooding the compression chamber.
- Typical sites: workshops, garages, small plants and construction sites running piston compressors.
It is not the right choice for oil-flooded screw or vane compressors, and not for centrifugal compressors, which lubricate only their bearings and gears and usually call for a turbine-type oil. Gas compressors and refrigeration compressors have their own categories in ISO 6743-3.
What happens if you use the wrong compressor oil?
The wrong compressor oil leads to carbon on valves, wear, sludge and varnish, and water problems.
- Carbon on valves: oil that breaks down at discharge temperature leaves deposits on valves and in discharge lines, which reduces efficiency and raises temperature further.
- Wear: a viscosity too low for the operating temperature cannot hold a film between rings and cylinder walls.
- Sludge and varnish: oxidation thickens the oil and blocks filters and coolers. This is the main failure mode in flooded screw compressors, which is why their oils are formulated differently.
- Water problems: compressed air carries moisture. An oil that does not separate from water emulsifies, rusts parts and shortens drain intervals.
Checks before you buy or switch
- Read the category, not just the viscosity, in the compressor manual or on the oil label currently in use.
- Do not mix base oil types without checking. Synthetic compressor fluids, especially polyalkylene glycol (PAG) types, may not be compatible with mineral oil. Drain and flush as the compressor maker recommends when changing type.
- Follow the manufacturer’s drain interval, and shorten it if the oil turns milky, darkens quickly or the compressor runs hot.
- Ask for data, not adjectives: a technical data sheet with test methods, and a certificate of analysis for each batch.
Zhongtian supplies L-DAB, L-DAG and L-DAJ compressor oils in several viscosity grades and makes to order, so limits such as viscosity and pour point can be written into the purchase specification.
Frequently asked questions
Can I use L-DAB 46 in a rotary screw compressor?
Not in an oil-flooded screw compressor. Those machines need an oil from the DAG, DAH or DAJ categories, even when the required viscosity is also ISO VG 46.
Does the D in L-DAB stand for detergent?
No. D is the compressor family in ISO 6743-3, A means air compressor, and B is the medium-duty reciprocating category.
Is L-DAB 46 the same as any ISO VG 46 compressor oil?
Only if that oil is also made for reciprocating compressors. ISO VG 46 describes viscosity alone. Check the category on the data sheet.
Sources
- ISO 6743-3:2003, Classification, Family D (Compressors)
- ISO 6521-1:2019, Specifications of categories DAA and DAB
- ISO/TS 6521-2:2021, Specifications of categories DAG, DAH and DAJ
- ORLEN Oil industrial product catalogue, CORALIA L-DAA and L-DAB
- GB/T 7631.9-2014, Classification of lubricants, Family D (Compressors), modified adoption of ISO 6743-3:2003
- Zhongtian product data sheets for L-DAB, L-DAG and L-DAJ compressor oils