Published: 03/12/2025
Oil-Injected vs Oil-Free Screw Compressors: Pros & Cons
In large-scale industrial environments, compressed air is often a major requirement to keep production lines flowing. It’s used to power up both pneumatic tools in manufacturing and support critical processes in various other industries.
If you’re not sure which air compressor to choose, there are two key types to bear in mind: oil-injected and oil-free screw compressors. So, what is the difference?
You can find out more about the different types of compressors in our article: What are Compressors Used For?
How do screw compressors work?
Oil-Injected screw compressors
Most heavy industries use oil-injected screw compressors. Typically, they’re considered more reliable than oil-free alternatives and last better when in constant use. The oil used to lubricate moving parts reduces friction and disperses heat, which reduces the risk of breakdowns.
You’ll find this compressor type in the following industries:
- Manufacturing premises
- Automotive warehouses and repair shops
- Oil and gas industry
Oil-free screw compressors
An oil-free screw compressor in the UK is exactly how it sounds. It doesn’t use any oil whatsoever as a means to lubricate interior components. Instead, this type of compressor relies on pre-lubricated bearings as it operates. In fact, it is the gearbox that is the critical tool, as it connects to the drive motor and powers the two compressor elements.
Oil-free models are more commonly found in the medical, aerospace and food industries, where air purity is a non-negotiable.
Oil-injected screw compressors: Pros and cons
Pros
Durability
Oil-injected screw compressors are designed to withstand the test of time.
During operation, the injected oil acts as both a lubricant and a cooling agent. This reduces friction between the compressor’s moving parts and protects the internal components from excessive wear.
Cost-effective
Oil-injected screw compressors are considered budget-friendly (both in terms of the initial purchase and ongoing maintenance). Therefore, they’re particularly well-suited to heavy-duty manufacturing environments where consistent high output is critical.
Routine upkeep typically only involves occasional oil changes and filter replacements, as opposed to full technical repairs.
Produce minimal heat and noise
The oil inside the system works not just to keep parts lubricated, but it also absorbs sound and disperses intense heat during compression.
These factors are beneficial in industries of small-scale and quiet environments, where minimal disturbance is compulsory.
Cons
Poorer air quality
One of the main drawbacks is the potential risk of oil contamination. During operation, small traces of oil can pass through the filtration system and enter the air stream.
These traces are extremely minimal. Typically, the air is still accepted in predominantly engineering and automotive industries, for example. However, it would not be deemed satisfactory in more sensitive industries (such as food, chemical and medical trades).
Oil-free rotary screw compressors: Pros and cons
Pros
100% pure air
Oil-free compressors produce 100% clean air in accordance with international air quality standards (ISO 8573-1 Class O – the highest standard of air purity).
More compact in size
This compressor type is more compact than the larger oil-injected models, making it a smart choice for smaller premises with limited space.
Environmentally-friendly
Oil-free compressors are highly sustainable – they eliminate the need to discard oil after use. Plus, there is zero risk of oil leaks.
Cons
Potential shorter lifespan
Without the lubrication of oil, internal components could possibly deteriorate. Over time, this can lead to the breakdown of piston rings and rotors. Costly repairs or even a full compressor replacement may be required as a result.
Which type of compressor should you choose?
Factors such as the day-to-day processes and air quality output standards play a role in determining which air compressor is the most suitable for you.
We’ve been in the engineering industry for over 30 years now, so we’re here to help you find the best compressed air solution for your needs. Whether your current compressor is BOGE, Worthington, Atlas Copco, Ingersoll Rand or any other model, we can service, maintain, and place it under warranty.
If you’re looking for a new compressed air system, we can also accommodate this.
Get in touch with Air Supply Manchester today.