GL4 vs GL5

GL ratings on gear oils represent their level of protection. GL-4 gear oils are designed for compatibility with yellow metals such as brass, bronze and copper alloys; while GL-5 gear oils contain sulfur-phosphorus EP additives which may corrode these metals. GL4 vs GL5 are two similarly popular models.

Applying GL-5 gear oil in a vehicle with yellow metals could damage its transmission and accelerate wear-and-tear, so it is crucial that you choose an appropriate gear oil for your car. Just like Dexos 1 vs Dexos 2, we make a detailed comparison. We will compare different features for GL4 vs GL5.

What is GL4?

GL-4 gear oil is designed specifically for manual transmissions and transfer cases, offering thinner viscosity than its GL-5 counterpart and being compatible with bronze and brass components. Furthermore, it contains EP additives which protect gears against wear and tear.

Comparable to GL-4 gear vs GL-5 features higher levels of extreme pressure (EP) additives that make it suitable for high-speed and heavy load applications. Furthermore, its thicker composition can withstand more heat and friction.

GL-5 gear oil is designed for differentials, automatic transmissions and final drives; it’s also compatible with yellow metals such as copper and bronze. However, it should be noted that when used in manual transmissions with synchronizers using EP additives can attack and corrode them and cause severe transmission system damage – so be sure to refer back to the owner’s manual or consult a technician to make sure you use the appropriate type of gear oil.

What is GL5?

GL-5 gear oil was designed specifically to lubricate hypoid gears in automotive axles that operate at high speeds and heavy loads, and has superior extreme pressure (EP) properties than its GL-4 counterparts.

Contrary to GL-4, gl-5 utilizes more sulfur and phosphorus for bonding metal surfaces together – thus helping prevent galling and seizure of gears. Furthermore, its EP additive content exceeds that of GL-4.

However, gl-5 can be detrimental to copper synchronizers in transmission systems. Analyses typically reveal two to four times more copper impurities in samples from gl-5 oils compared to those containing gl-4 oils.

Viscosity is also one of the key distinctions between Gll-4 vs Gl-5 gear oils; with GL-4 boasting a thinner viscosity that makes it flow more freely – ideal for older cars with manual transmissions; on the other hand, GL-5 features thicker viscosities which makes it more suitable for newer models featuring automatic transmissions.

Differences Between GL4 and GL5

GL4 vs GL5 is an important issue for those who are more sensitive to their cars, even though it gives similar results in many areas. GL4 vs GL5 gear oils both lubricate and protect your vehicle’s transmission, but each offers different properties. Their main difference lies in the amount of extreme-pressure additive (EP additive) contained within. EP additives consist of sulfur or phosphorus compounds that create an extra protective barrier between gears to keep them from damaging each other when they rub against each other. GL4 vs GL5 are not dramatically different products from each other in terms of price.

GL-4 gear oils are recommended for manual transmissions and transaxles that operate under moderate speed and load conditions, including brass and bronze metals. They are also compatible with yellow metal alloys. GL4 vs GL5 is one of the most curious comparisons about motor oil in recent years.

GL-5 gear oils are specifically tailored for automotive axles with hypoid gears operating under high speeds and heavy loads, featuring hypoid gears with two times as much EP additive than their GL-4 counterparts to offer superior protection, performance, and efficiency for these systems. Incorporating this oil in non-hypoid systems may result in damage to gears and synchronizers – only use it if your hypoid gear system uses hypoid gears! It is enough to mention these for GL4 vs GL5.

GL-4 oils contain less extreme-pressure additives than their GL-5 counterparts, thus not providing as much protection to gears. Furthermore, their lower viscosity makes them better suited to conventional transmissions than synchronized gears.

GL-5 oil contains more EP additives than its GL-4 counterpart, and their high concentration can cause corrosion on non-ferrous metals like brass synchro rings, rendering GL-5 unsuitable for use in transmissions that were designed to use GL-4. Furthermore, this increased exposure to brass could even result in stripping from within synchronizers; hence it’s vital that you read manufacturer recommendations prior to selecting your gear oil.


Can I Use GL5 Instead of GL4?

GL-5 gear oil is designed for spiral bevel and hypoid gears in larger vehicles with higher speeds and loads. Featuring more extreme-pressure additives than its GL-4 counterpart, this heavy-duty solution makes an excellent choice.

Gear oil with greater shear stability has an edge when it comes to withstand higher temperatures and heavier loads without breaking down or degrading; however, using the wrong type in your car could damage its transmission or lead to other complications.

Pouring gl-5 into a manual transmission will lead to shift quality issues because it contains more EP additives than gl-4. Furthermore, its sulphur and phosphorus additives could react with bronze components like synchro rings and damage them, leading to extraneous noise or leaky oil seals and extra noise levels in general. Furthermore, using it in transfer cases will accelerate their burning as well as damage their bearings and shaft.

Can you mix GL4 and GL5?

Mixing GL-4 and GL-5 gear oils may be possible, though not recommended. Each serves a distinct function, and using an inappropriate type can harm either your transmission or differential.

Which one is better: GL4 vs GL5?

GL-5 gear oil boasts higher extreme pressure ratings than GL-4, making it more suitable for high-speed and heavy load applications, such as vehicles with larger axle offsets or hypoid gears. It should also be considered in situations that involve vehicle offsetting.

On the other hand, GL-4 gear oil is best suited for moderate speed and load applications, being compatible with bearings made of brass and bronze bearings and synchronizers. This is a good example for GL4 vs GL5.

Be mindful that while GL-5 and GL-4 may seem similar, they should never be mixed or substituted with each other. Mixing these types of gear oil may damage your vehicle’s transmission; using GL-5 in a transmission designed for GL-4 may lead to reduced extreme pressure ratings which in turn leads to early wear and failure of gears. For optimal protection and optimal performance as well as to avoid costly repairs or replacements it’s wise to stick with what has been recommended by your vehicle manufacturer for optimal protection and performance. We made a comparison like in “10w30 vs 5w30“.

Juan Gibson

Juan is an automotive engineer and an avid car enthusiast. He has over 15 years of experience in the car industry. In my free time, I write blog posts about cars, models and etc.

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