How to tell the difference between oil and transmission fluid

The simplest answer to the difference between transmission fluid and gear oil is in the purpose for which they are designed. Transmission fluid is engineered to work with automatic transmissions, whereas gear oil is typically intended to work with manual-type gear boxes. However, for a comprehensive understanding of the two fluids, the properties demanded of them and how they differ, we must first explore the key differences between transmissions and gearboxes.

While both pieces of equipment are required to perform the same role of enabling gears to change and control the force, speed, and direction of a vehicle, they achieve their own results using different methods and therefore need different supporting fluids for operation.

Automatic transmissions

Automatic transmissions work in a system that involves multiple gears switching automatically in answer to the different demands of an engine. Gears within an automatic transmission are usually far smaller and greater in number than those contained in a manual system. For effective operations, transmission fluid must not only lubricate but transfer power from the vehicle’s oil pump to its clutches, the machinery that controls gear movement.

Key properties of transmission fluid

Essentially, transmission fluid is a hydraulic oil and an exceptionally thin one. To lubricate the systems delicate components, it must have a low viscosity so it can flow freely transferring power from the vehicle engine to its transmission.

Transmission oil contains detergent to ensure no build-up of debris occurs in channels between parts that might negatively affect operation. It must also have heat-resistant properties as it is required to act as a coolant, transferring heat away from working parts when friction occurs. With a much lower boiling point than gear oil, it typically needs additives to increase its lifespan.

Transmission fluid has also been designed for anti-foaming capabilities, keeping unwanted air out of the lubricant, so it doesn’t interfere with force being transferred.

Manual gearboxes

Manual gearbox operations are based on a system that features two individual shafts and gears that work together when the user interacts with a gearstick and clutch, and because of this, manual systems generate a lot of heat, force and friction. To answer these issues, gear oil has to be capable of making these transitions between gears as smooth and seamless as possible, preventing parts becoming damaged as they shift between positions.

Important qualities of gear fluid

Gear oil is far thicker than standard motor oil. With a high viscosity, the oil can make sure the connected gears are always lubricated and keep them cushioned against the shock and sudden impact when they interact.

As manual gearboxes generate an increased amount of friction, they also create a great deal of heat, so gear oil is engineered to withstand exceptionally high temperatures and safely transfer the heat away from the gearbox. The oil must also be able to operate effectively under extreme pressure, so today’s products offered by manufacturers like Fuchs and Mobil often contain specially formulated additives to deliver improved performance and greater oil stability.

Just as your body has blood and other vital fluids running through it to keep you alive, so does your car. Beyond the gasoline you put in, there are several different types of fluids that you'll find in any vehicle. It's important to know what each does and how to identify them in case of leaks. Some fluids and fluid levels are easy for you to check yourself. Others are a bit more tricky and may require the expertise of a professional like San Francisco Automotive Solutions.

Here are some of the common fluids in your car:

1. Motor Oil

Obviously, oil is the most important fluid in your vehicle. It keeps engine parts lubricated. It is easy to check the oil level and consistency with the dipstick. It is typically light brown in color. If you check the dipstick and the oil is very dark brown/black or unusually thick in texture, it is definitely time for an oil change. It could also be the sign of a bigger problem that you may want to get checked out.

2. Transmission Fluid

There is another dipstick under your hood, and that one measures your transmission fluid. The fluid will usually be pink or red in color and should have a very viscous feeling if you touch it. Again, if it appears thick or dark, it could be the sign of a problem. You need your transmission fluid performing properly to keep vital transmission components well lubricated.

3. Brake Fluid

Brake fluid gives power to your brakes and helps you stop your car. So needless to say, it is very important. It is typically light brown or yellowish in color. There is a reservoir for your brake fluid (usually near the back of the engine compartment). The fluid level should always be near the top.

4. Coolant/Radiator Fluid

Your radiator prevents your car from overheating and the coolant/antifreeze/radiator fluid inside is vital for this function. It is usually bright yellow or greenish. You can easily check the radiator fluid level and add more if needed. Just be careful removing the cap if the engine is still warm. If it has a strong burnt smell, you may want to get it checked out or flushed.

5. Power Steering Fluid

Most modern vehicles will have power steering and therefore will require power steering fluid to make the system work properly. You can check the reservoir with a dipstick. The color is typically red, pink or sometimes clear. If it is dark, you should get it checked out.

6. Air Conditioning Coolant

If your car has air conditioning, the coolant (also known as refrigerant or Freon) will generally be very bright in color. Leaks should be very noticeable and you'll want to have a professional deal with it. Air conditioning coolant can be dangerous, so unless you are really knowledgeable and careful you probably won't want anything to do with it.

7. Windshield Washer Fluid

This is not really a vital fluid in your car, but it serves a purpose. Most windshield washer fluid is light blue. The reservoir tank is easy to find and fill under your hood.

If your vehicle is leaking any fluids or you just need routine maintenance to check, flush or refill any of your car's vital fluids, contact San Francisco Automotive Solutions (formerly All American Automotive). We'll be glad to help you out with all of your car's fluid needs. Call us today at (415) 523-0515 or schedule a service appointment online today.

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