Updated at: 26-06-2022 - By: Lucas

A lot has been said about what oil is best for automatic transmissions. But few people have talked about how to choose the right gear oil for a car with a manual transmission.

Many car owners don’t even bother to change their engine oil on time, which is a shame. So you can see why very few people actually change their cars’ transmission fluid. You are one of the few people who wants to know what kind of gear oil is best for a manual transmission. Find out about the 3 kinds of manual gearboxes.

Even though each car’s manual says what kind of gear oil it needs, people have been arguing about this since cars were first made. Some mechanics recommend high viscosity gear oil, while others stick to ATF oil for both automatic and manual gearboxes. The next choice is whether to use synthetic oil or mineral oil.

When should you replace Manual Transmission Oil?

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Well, when there are so many different ideas, we say to go with what the car company says. But remember that the manufacturer’s suggestion is for a typical user. What I mean by this is that you, the car’s driver, know how and where the car is driven well. How much does it cost to change the fluid in a transmission?

Based on this, you should use the advice of the manufacturer as a starting point and make your own decisions.

If you drive in an area with hills, your transmission has to work harder every day than if you drove on flat roads. In the same way, if you drive with a lot of energy, your transmission has to deal with a lot of stress.

If you drive your car on mountain roads, you should change the transmission fluid every 45,000 km. On plain roads, the same car won’t need it before 80,000 km. Most car makers say to change the oil every 80,000 to 100,000 km.

Some manufacturer that say their transmission oil is lifetime?

“Lifetime” transmission oil is now used by a lot of car companies, like BMW. But the word “lifetime” isn’t very clear because it could mean either 5 years or 50 years. Imagine a BMW running in 50 years with oil that lasts “for life.” THESE things will never happen.

If you care about your car, you should at least change the transmission oil every 80,000 km. This is not a hard job, and it shouldn’t take more than 30 minutes to finish. If you want your shifts to be smoother or your car to last longer in harsh conditions, you should take the word “lifetime” out of your owner’s manual.

Exceptional situations when gear oil change is required

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Even if you are supposed to change the transmission fluid at a certain time, there may be times when you need to do it before. One common situation is when you think that water got into your transmission or transfer case. Water can get into the transmission while driving on flooded roads. If you don’t change this right away and keep driving the car normally, it can do a lot of damage to the gearbox.

Also, if you fixed a transmission leak, make sure the gear oil is back up to the right level. It’s easy to forget about it, which could ruin your gearbox if it runs out of oil.

Selecting the Right Gear oil for your manual car?

Now we have a general idea of when to change the oil in the transmission. But let’s talk about what kind of oil a manual transmission needs.

The viscosity of transmission oils is higher than that of engine oils. For example, gear oil is often given a number rating like 80W-90.

But engine oil and transmission oil are not the same just because of how thick they are. Both oils have different things added to them.

There are both metal and rubber parts in a manual transmission. Steel can be used to make the gears, while a softer metal like Brass can be used to make the transmission synchronizers.

What works well with one metal might not work well with another metal. So, a big part of choosing the right transmission oil is finding the oil that works with it.

To do this, you need to know the GL rating of the gear oil. Most of the time, GL-4 and GL-5 are given. GL-4 is usually found in cars that are used every day. The GL-5 is recommended for cars and trucks with gearboxes that are put under a lot of stress.

Your car’s owner’s manual will tell you for sure what the right GL rating is for the transmission.

If you look in the manual, you might find that MT-1 rating is suggested. In non-synchronized gearboxes, MT-1 grade oil is used. It is often used in heavy-duty trucks and in some transfer boxes with all-wheel drive.

Just Tell me what oil should I use?

Well, as you can see, I can’t tell you what oil to use without knowing what kind of car you have. But the transmission oil specs are in the owner’s manual, so the manufacturers have taken care of this.

Yes, you can find both the right GL rating and the right viscosity in the owner’s manual. But if you can find the right grade of synthetic transmission oil, that is always better than mineral oil.