Although manual and automatic transmission oils are lubricants used in automotive vehicles, their duties vary in complexity. Understandably, automatic transmissions are significantly more complex machinery than manual systems. Consequently, the liquids they need to operate properly are also complicated. In this blog, we will examine the purposes for which automatic and manual transmission fluids are assigned to highlight their variations.
Understanding the Functions of Automatic Transmission Fluids (ATFs)
Among other things, ATF has to be a hydraulic fluid, provide appropriate frictional requirements, lower heat, and shield the gear against wear.
Serving as a Hydraulic Fluid
An automatic transmission changes gear using pressurized fluid. ATFs behave as hydraulic fluid. When a car’s onboard computer needs a gear shift, it sends an electrical signal to the suitable transmission solenoid. After that, this solenoid engages the appropriate gear and guides fluid via a sophisticated network of valves and body passages. The ATF hydraulically squeezes multiple plates inside the clutch pack to transmit power to the gearbox output shaft, connecting the engine to the wheels.
This process happens quickly and mostly invisibly when a transmission runs as it should. On the other hand, a high viscosity of the transmission fluid would not allow it to flow quickly to produce the confident, crisp changes sought. ATF is, therefore, far thinner than manual transmission fluid and has a lower viscosity index.
Additionally, negating its value as a hydraulic fluid is that automatic transmission fluid accumulates foam. Along with wear to gears, elongated and uneven shifts occur as foam bubbles shatter under pressure. ATFs also contain foam inhibitors to fight this.
Providing the Right Frictional Requirements
Pressurized ATF engages the correct gears by squeezing the clutch packs together. Comprising bare metal plates and other plates covered with friction material, clutch packs are designed to maximize the driving experience for the vehicle user; disengagement and involvement have to flow naturally.
Whether this complicated choreography of fluid and moving metal generates exact shifts or has drivers changing transmission fluid depends on the frictional characteristics of the ATFs. ATF is therefore designed to provide particular frictional characteristics that are not needed in manual fluids.
Fights Heat
Heat breaks down the fluid by oxidation and is the enemy of ATF. Degraded ATFs produce varnish and sludge deposits that can block small oil passageways and cause harsh clutch shifts, jerks, and hesitations. Running hotter than manuals, automatic transmissions call for fluids with more heat protection.
Protection of Gears Against Wear
At last, automatic transmissions include sun, ring, and planet gears that require lubrication to prevent wear. The automatic transmission oil must build a strong fluid coating on all metal surfaces to prevent metal-to-metal contact and control wear.
Understanding Manual Transmission Oil
While less complicated, manual transmission fluids empower smooth shifts, enabling shift sensation, combating wear, and component protection.
Enabling Smooth Gear Shifts
A smoothly shifting manual gearbox links drivers to their cars. Many car aficionados avoid transmission fluids that cut this link. Although both manual and automated fluids provide seamless transitions, their component design is distinct.
Mostly fitting for manual transmissions are synchronizers. The synchro is designed to match the gear engaged in speed, allowing a seamless gear change. Without this, the spinning gears turning at various speeds would never interlock as needed.
Two main parts comprise the synchronizer unit: the sleeve and the blocker, sometimes known as the synchronizer ring. The sleeve moves to first gear and then locks onto the gear’s engagement teeth when a driver chooses the first gear, for instance. The second gear is chosen by the sleeve moving the other way and depressing the clutch pedal. But before the sleeve can lock on, the component’s spinning speed must be matched to prevent clashing.
A high viscosity of the best manual transmission fluid prevents shifting until the transmission heats up, or abnormally high temperatures can develop during running. On the other hand, very low viscosity can cause the synchronizer and teeth to engage too quickly, resulting in forceful shifts, grinding, and significant transmission wear.
Fight Wear
Like with an ATF, manual transmission fluid has to guard components against wear. A higher viscosity index found in manual transmission fluids assists the fluid in providing a thick and durable coating, delivering greater protection levels.
Protecting Brass Synchronizers
Usually made of brass, a softer substance than most metals, manual transmission synchronizers are susceptible to certain lubricant additives that damage the synchronizers and are inappropriate for brass. High-quality manual transmission fluids are thus designed to be compatible with brass synchronizers, ensuring their continued protection.
Always use the right fluid for your vehicle’s transmission if you want the best driving experience and the maximum degrees of performance and protection.
Does Transmission Fluid Need to be Changed?
Transmission fluid oxidizes with time and gets sludge and particle-polluted. Transmission fluid should be checked often, even if it doesn’t need to be replaced as often as motor oil.
If the transmission fluid level is low or the fluid begins to break down, the car could shift badly. Running low on fluid could cause catastrophic failure or costly repairs by damaging transmission components.
How Often Should Transmission Fluid Be Changed?
The kind of transmission and the mechanical loads it has to bear determine the response. Changing transmission fluid every 30,000 to 150,000 miles (48,000-240,000 km) is usually advised, but sometimes it’s not advised at all.
Depending on the year, make, and model, the original equipment manufacturer’s (OEM) suggestions for how often to replace automatic gearbox fluid include a broad range of mileage. Many OEMs also advise replacing transmission fluid more regularly if your driving patterns match most others and fall within the “severe” classification (towing, hauling, everyday short excursions shorter than 10 miles [16 km], etc.).
These variations show the need to follow the owner’s manual’s advice. Usually shown in a table at the rear, it will offer maintenance suggestions. Many OEMs have online digital owner’s manuals; if you have lost yours, attempt a simple search.
