13/05/2026
Understanding Oil Seals: What They Do, How They Are Measured & Common Brands
Oil seals are one of the most important components in machinery, vehicles and industrial equipment. Even though they are small parts, they play a major role in protecting machines from leaks, contamination and costly damage.
At Perkins Seals, we understand how important it is to get the right seal for the right application. Here’s a simple guide to understanding oil seals.
⸻
🔧 What Does an Oil Seal Do?
An oil seal is designed to:
✔ Prevent oil or grease leakage
✔ Keep dust, water and dirt out
✔ Protect moving components such as shafts and bearings
✔ Maintain pressure and lubrication inside machinery
Oil seals are commonly used in:
* Vehicles
* Gearboxes
* Hydraulic systems
* Pumps
* Mining equipment
* Industrial machinery
* Agricultural equipment
Without a good oil seal, machinery can lose lubrication, overheat, wear out faster or even fail completely.
⸻
📏 How Are Oil Seals Measured?
Oil seals are usually measured using three main dimensions:
1️⃣ Inner Diameter (ID)
This is the shaft size — the inside measurement of the seal.
2️⃣ Outer Diameter (OD)
This is the housing or bore size — the outside measurement of the seal.
3️⃣ Width / Thickness
This is how thick the seal is.
⸻
Example:
35 x 52 x 7
This means:
* 35mm = Inner Diameter
* 52mm = Outer Diameter
* 7mm = Width
Measurements can be in metric (mm) or imperial (inches) depending on the machinery.
⸻
🧱 Common Oil Seal Materials
Different applications require different seal materials. Some common materials include:
🔴 Nitrile Rubber (NBR)
The most common material.
Good for:
* Oil resistance
* General industrial use
* Standard temperatures
🔵 Viton (FKM)
A stronger, premium material.
Best for:
* High temperatures
* Chemicals
* Heavy-duty applications
⚫ Silicone
Used where flexibility and temperature resistance are important.
🟤 Polyurethane (PU)
Very durable and commonly used in hydraulic applications.
⸻
🏭 Common Oil Seal Brands
There are many seal brands on the market, but some are known for their quality and reliability.
⭐ SOG
One of the most recognized brands in the industry.
SOG seals are known for:
✔ Durability
✔ Precision fit
✔ Good resistance to wear
✔ Reliable performance in automotive and industrial applications
Because of their consistency and quality, many customers specifically request SOG seals for vehicles, pumps and industrial machinery.
⸻
Other Common Brands
* NOK
* SKF
* TTO
* Corteco
* National
* NAK
Each brand may vary slightly in:
* Rubber quality
* Lip design
* Spring tension
* Durability
That’s why choosing the correct brand and specification matters.
⸻
⚠ Why Correct Sizing Is Important
Using the wrong size or incorrect material can cause:
❌ Oil leaks
❌ Premature wear
❌ Overheating
❌ Shaft damage
❌ Machine downtime
Always make sure:
✔ Measurements are correct
✔ Material matches the application
✔ The seal is properly installed
⸻
🔧 Need Help Identifying a Seal?
At Perkins Seals, we assist customers with:
✔ Seal identification
✔ Size matching
✔ Metric & imperial conversions
✔ Industrial & automotive applications
📍 10 Deptford Street, Belmont
📲 +263 778 487 792
You can send us:
* A size
* Sample
* Picture
* Part number
…and we’ll help you get the right seal quickly and professionally.
