Industrial gear oil or GL-5: how to tell ISO VG 220 from a vehicle gear oil
Cover photograph: an enclosed industrial gearbox, by Moeclee, CC BY-SA 3.0. The file was resized for this page. It shows the kind of equipment being discussed and is not a product offered here.
An ISO VG number and an API GL-5 label describe different gear-oil requirements. Check the gearbox or axle manual before treating an industrial gear oil and a vehicle axle oil as substitutes.
1. Start with the gearbox or axle
Record the equipment maker, model and the lubricant specification written in its manual. An enclosed industrial reducer and a vehicle axle can both be described as gearboxes, but they often require different oils. If the manual is unavailable, ask the equipment supplier before treating the name of the oil now in use as the specification.
2. Read GL-5 as an axle designation
API Publication 1560 describes GL-5 as a lubricant for gears, particularly hypoid gears, in axles that operate under high-speed shock load and low-speed, high-torque conditions. The viscosity of an automotive gear oil is stated as an SAE grade, such as 80W-90.
The same publication says that several older designations, including GL-4 and MT-1, are not in current use. If a catalogue line still mentions MT-1, check it against the current product document and the equipment requirement rather than assuming the older designation is still the one to order.
3. Read ISO VG 220 as a viscosity grade at 40°C
ISO 3448 names an industrial viscosity grade by its kinematic viscosity at 40°C. For ISO VG 220, the midpoint is 220 mm²/s and the permitted limits are 198–242 mm²/s. The grade does not state whether the oil is suitable for a particular gearbox, and it is not an SAE grade. Do not convert ISO VG 220 into 80W-90, or the other way around, and then treat the two oils as equivalent.
4. Match one catalogue line to the quoted product
This catalogue lists an EILONG vehicle gear oil as API GL-5 / MT-1, with SAE grades 80W-90, 85W-90, 85W-140 and 140. It lists EILONG industrial gear oils in the CKB, CKC, CKD and CKE series across multiple ISO viscosity grades. TRIOSD GearMax L-CKD is listed with ISO VG 150, 220 and 320 and is positioned around DIN 51517-3 CLP. Confirm the exact grade, current documents and availability of the product in the quotation. A catalogue line is not a gearbox approval.
- Gearbox or axle model, and the specification named in the manual
- The required ISO VG or SAE grade, written separately from GL-5 or CKD
- Pack size, quantity and destination
- Request the current TDS and SDS for that exact grade
5. Keep the two orders separate
If the manual asks for an ISO VG grade and an industrial gear-oil type such as CKD or CLP, a GL-5 axle oil is a different request. If the manual asks for GL-5 and an SAE grade, an ISO VG industrial oil is a different request, even when the oils feel similarly thick.
Where the gearbox or axle contains yellow metals, ask the equipment manufacturer about the extreme-pressure additive before using a GL-5 oil. This catalogue does not decide that question. Match the quotation to one of the two requests, and ask for the TDS of the exact grade.
Questions about this topic
Can GL-5 replace an industrial gear oil specified as ISO VG 220?
Not from those two labels alone. Compare the gearbox requirement with the documents for the exact product before changing the oil.
Is ISO VG 220 the same as SAE 80W-90?
No. They belong to different viscosity systems. A similar thickness at one temperature does not make the oils interchangeable.
Catalogue grades in this guide were checked against the product listings on this website and the standards named above. CloudBridge coordinates the inquiry. The manufacturer named on the quotation confirms the current specification.
