Gear oil is the most beneficial substance that helps your car or truck run smoothly. The main difference between GL-4 Vs GL-5 gear oil is Extreme Pressure (EP) additives and their viscosity grade. You can use GL-5 instead of GL-4 to get faster transmission. GL-5 is a fully synthetic gear oil with viscosity grade SAE 75W90. On the contrary, with SAE 80W90 viscosity grade, GL-4 is also a fully synthetic gear oil. So it can be said, that GL4 is thicker oil than GL5 gear lubricants.
For the thickness of GL4, it can deliver the highest performance in high-temperature conditions. But GL5 performs well in overall conditions and provides sufficient gear protection. To clarify your doubt and confusion while choosing a single one between GL-4 and GL-5, read this article from beginning to end.
GL-4 vs. GL-5 In Table
| Basis of comparison | GL-4 | GL-5 |
| Manufacturer | Redline and Valvoline | Same as its counterpart |
| Package information | Bottle | Bottle |
| Oil Types | Full synthetic with SAE 80W90 viscosity grade. | It is also a 100% synthetic gear oil with a 75W90 viscosity grade. |
| Viscosity Grade | GL-4 oils contain fewer Sulphur compounds to reduce the viscosity of the additives. | This oil has a higher viscosity |
| Oils weight | The weight is around 1.5 pounds to 2 pounds. | 7 pounds |
| Package Dimensions | 2.25 x 4.75 x 7.5 inches | 7.5 x 4 x 11.25 inches |
| Pour Point | -45 degree Celsius | -42 to -45 degrees Celsius |
| Density | It is denser than its counterpart. | The 75W90 viscosity grade is less thick than GL-4. |
| Suitability | Widely used in Nissan, Toyota, Mazda, Mitsubishi, Mendola transmission, and Atlas transfer cases. | It is a perfect addition for all types of passenger cars, light lifting trucks, and racing vehicles. |
| Key feature | These gear oils feature anti-corrosion additives for better transmission. | It contains extra friction modifiers for better lubrication under extreme conditions. |
| Performance in cold weather | It depends on the viscosity grade. It delivers better performance in cold weather. | It provides better performance in extremely cold conditions and in the cold as well. |
| EP protection | The EP protection is lower compared to GL-5. | As the rating is higher, the EP protection is also higher. |
| Costs | Prices range from $15 to $20 | The price is slightly higher compared to GL-4 but it is worth buying for its tremendous value. |
GL-4 vs. GL-5 gear oil: Major Differences
You may find a bird’s eye view idea from the table. Now, in this section, you’re going to see detailed differences between them.
Basic
GL-4 is a traditional API-based superior quality manual transmission fluid or oil for any traditional engine car. This oil is capable of restricting wear and rust while improving speed. With standard SAE grade, it performs superbly and protects against early wear.
On the contrary, with the higher rating and anti-corrosive additives, the GL-5 provides smoothness while driving. For its higher grade, it is totally Sulphur and phosphorus-based compounds that cling to the metal surfaces. That’s why they create polar attraction for better transmission and flow.
Viscosity grade
Viscosity matters a lot when it comes to your gear. And there is a crucial difference that might be considered. The GL-4 is a fully synthetic gear oil with a various range of viscosity. The major viscosity grade is 80W90 which means it is compatible in high-temperature conditions.
On the other hand, the GL-5 is also a 100% synthetic gear oil with a viscosity grade of 75W90. So it has better low-temperature viscosity and provides the utmost running of all kinds of surfaces. It is better in high temperatures and pressure as well.
Thickness
When talking about the density of these oils, GL-4 is thicker than its counterpart. This allows it to perform better at high temperatures by changing oil more frequently. As it is a higher-viscosity grade oil, it consumes more heat and provides optimum performance on hot days.
Counters, the GL-5 density varies from season to season. However, with a viscosity grade of 75w90, it keeps the applications running under cold temperatures. It gets thicker with high heat and gets thinner under colder conditions.
Applications
The GL-4 manual transmission fluid and multi-purpose oils are great additions for all types of commercial vehicles like automotive, passenger cars, auto, lift trucks, and bus standard transmission. In contrast, Gl-5 is a premium and innovative differential oil that comes for cars, light trucks (Ford Mustang, Toyota Tundra, Jeep Cherokee), heavy-duty operation, power plant equipment, etc.
Performance
It features anti-corrosive additives and anti-wear so that it can ensure top-notch performance till the end. It offers hasty shifts, smooth and exact synchronizer coefficient of friction, higher grade gear protection, and longer synchro lifespan.
On the other hand, the GL-5 has Ester base stocks and friction modifiers that provide additional slipperiness on lower temperature ranges to ensure smooth performance. It contains additional friction modifiers to reduce wear on the piston. Moreover, it delivers incredibly better lubrication under the harshest conditions.
EP additives
That can be said, EP additives are crucial distinctions. Both have Sulphur and Phosphorus compounds. They are corrosive so they attack the metal while the gear produces heat. However, the GL-5 has fewer additives than the GL-4 as it contains less Sulphur and phosphorus.
When talking about EP protection, GL-5 is ahead of GL-4. the higher the rate is, the higher EP protection. However, it does not say that the GL-4 is less workable.
GL-4 Gear Oil – Best for Multi-purpose Uses
As mentioned before, GL-4 is a low-compound manual transmission fuel for all types of passenger cars and bus standard operation. It is environmentally friendly and doesn’t have any harmful objects or chlorine. It is premium quality and durable gearbox oil with tremendous pressure additives. They are capable of resisting rust, and temperatures, eliminating stains, and corrosion, and eliminating notchy shifting.
It has low pour points and extreme temperature protection. It provides better lubrication over a wide temperature range. Further, it is Hypoid gear oil with anti-rust and anti-wear EP additives that prevent corrosion and protect the Hypoid gear. However, it is comparatively inexpensive and the highest quality OE standard product.
GL-5 Gear Oil – Best Overall Performance
An innovative, highly efficient, and standard SAE-grade transmission gear oil provides incredible performance. It contains extra friction modifiers to ensure a smooth clutch and handling over the harshest conditions. With a higher rate of 5, it ensures maximum protection in crowning conditions like speed, heavy loads, and torques.
It offers excellent lubrication to make the piston smoother running and additional slipperiness ensures smooth operation under low temperatures. It has superior shear permanency and is capable of reducing oxidation to eradicate unnecessary wear. The consistent viscosity and thickness ensure the highest performance in both summer and winter. It is made to last and offers the highest degree of protection for better handling, driving, long-lasting drain intervals, and better mileage.
Final Verdict
It is a hard nut to crack to identify which one is better between GL-4 and GL-5 gear oils. Both gear oils are EP and API grade. So here there is no debate and confusion. But the real difference is in the EP protection. Though they both have EP protection, GL-4 has less protection than GL-5 oil. However, if you want a better product on an affordable budget, the GL-4 is recommended. But if you want extreme and superb performance, better mileage, less wear, and consistent viscosity, you can go for GL-5 gear oil.
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