Compressor Oils / 5 min
Compressor Oil Equivalents: Correct Matching via ISO VG and DIN 51506
Reducing brand dependency or switching to more accessible products is a common approach for industrial compressors. However, when determining a compressor oil equivalent, looking only at the number on the container isn't enough. The viscosity class (ISO VG) and international standards (DIN 51506) must be carefully reviewed, without assuming brand equivalence.
Published by: Rotek Technical Content Team
Content is published based on manufacturer technical documentation and equipment requirements as the basis for final selection. This is general guidance and does not replace equipment-specific manufacturer approval.
Review our editorial guidelinesTable of Contents
- - Oil Needs by Compressor Type
- - ISO VG Viscosity Classification
- - DIN 51506 Standards (VDL, VBL, VCL)
- - Synthetic and Mineral Oil Compatibility
- - OEM Approval and Correct Product Matching
Oil Needs by Compressor Type
Because screw and reciprocating compressors work on different operating principles, their expectations of oil also differ. Reciprocating compressors reach higher compression temperatures and need products resistant to carbonization. Screw compressors need specialty formulations that quickly separate the air-oil mixture (demulsibility).
ISO VG Viscosity Classification
The first step in finding an equivalent is viscosity. Values such as ISO VG 46, 68 or 100 for the current oil should be matched directly. However, two oils sharing the same ISO VG class doesn't mean they're exact equivalents or that they'll deliver the same quality of performance — it only means their fluidity is similar at the same temperature.
DIN 51506 Standards (VDL, VBL, VCL)
The core standard determining compressor oil quality and performance is DIN 51506. VDL-class products offer the highest oxidation resistance for air compressors operating up to a discharge temperature of 220°C. If your current product is VDL grade, your equivalent choice must also be VDL-approved.
Synthetic and Mineral Oil Compatibility
Switching from a mineral-based oil to a synthetic (PAO or ester-based) oil improves performance. But when old and new oils mix, filter clogging can occur. If switching to a different base oil technology as an equivalent, the system must be fully drained and cleaned (flushed).
OEM Approval and Correct Product Matching
No product on the market can be treated as a direct copy (X = Y) of another brand's product. Every manufacturer has its own additive formulation. The viscosity and standards specified in the compressor manufacturer's (OEM) manual should be the reference, and final suitability requires OEM approval. Send us your product's brand, code and label information so our technical team can evaluate equivalent suitability for you.
Frequently Asked Questions
Can VG 68 be used instead of ISO VG 46?
No, it cannot. Choosing a viscosity that goes against the compressor's design raises temperature and can clog the separator filters.
What does VDL-class compressor oil mean?
VDL is the highest quality class under the DIN 51506 standard, describing oils with high resistance to carbonization at demanding discharge temperatures up to 220°C.
Can different-brand compressor oils be mixed?
No, they should not be mixed. Incompatible additive packages can cause foaming, which in turn carries oil into the system with the air.
What should I pay attention to when looking for a compressor oil equivalent?
The most important criteria are that the current product's ISO VG viscosity and DIN 51506 standard match exactly, and that the equivalent is suited to the compressor type (screw/reciprocating).