Transmissions and the fluids they use have come a long way over the last 50 years. One of the most misunderstood uses of fluid today is ATF in a manual gearbox. There are a lot of old school hot rodders that can’t wrap their head around why you would use an automatic transmission fluid in a manual transmission. As manual transmissions evolved over the years to include lined synchronizer rings, overdrive gears, and tighter bearing tolerances the type of fluid used had to evolve with it. ATF fluids flow better in cold temperatures, create less drag on moving components for more efficient power transfer, and do not deteriorate the friction materials that were added to the synchronizers.
Today you will rarely see a manual gearbox that doesn’t use an ATF or what now has evolved into a specific variation of ATF referred to as Synchromesh. Hypoid gear oils are still used in the older manual transmissions that called for them, but using them in the new
transmission is a no go as the hypoid gear oils are designed to withstand sliding actions at the meshing interface of bevel gears. Some hypoid oils contain additives that are corrosive to certain non-ferrous or “yellow” metals that are used in transmission parts like bushings and synchronizer rings. Also, the friction coefficient of some hypoid gear oils may be incompatible and can cause poor shifting. Both of these conditions can result in premature or excessive wear and failure in the newer
manual transmissions. We exclusively use the Royal Purple Synchromax in all our Tremec transmissions. After years of trial and error with other brands and styles of fluid we’ve found that the Royal Purple blend offers the best overall performance and shift feel out of the other fluids on the market.
The choices between the standard mineral oil fluids to the array of new synthetics can be a little overwhelming. There are good arguments to go in both directions, but the reality is that most all newer components are going to be designed to work with a fully synthetic fluid or synthetic blend of fluid to reduce frictional power losses. Also keep in mind that all synthetic fluids are not created the same as some are mineral based with synthetic additives and others are a fully synthesized version. Take the time to research which fluid is recommended or will work best for your particular situation as most manufacturers will void the warranty if the incorrect fluid is used.
Transmissions are integral to any car, manual or automatic. Without the proper fluids, your transmission will fail, and without a functioning transmission, your car is basically a huge paperweight! At Zumbrota Bearing and Gear, we offer a complete line of new, used, and remanufactured transmissions in Zumbrota, MN.
We remanufacture and sell transmissions, and we know firsthand how improper maintenance can destroy a good system. When you buy a car, be aware of the correct fluids it requires, whether you own a manual or automatic.
While some manual transmissions now use automatic transmission fluid (ATF), most manuals use a variety of fluids for optimal engine and gear function. Gear oil isn’t the same thing as ATF, and knowing the differences can make or break your car.
ATF Basics:
• ATF is a complex fluid full of lubricants and detergents that keep the transmission
running smoothly with minimal wear. ATF also works as a hydraulic fluid for power steering systems and some 4WD cases in automatic cars.
• Along with lubricant and detergent, ATF also contains a combination of additives including anti-wear additives, additives that block rust and corrosion, dispersants and surfactants that protect and clean metal parts in a transmission, kinematic viscosity and viscosity index improvers, seal swell additives that increase rotational speed and temperature
range, anti-foam additives, anti-oxidation compounds, cold-flow improvers, high-temperature thickeners, gasket conditioners, pour point depressant, and some form of petroleum dye.
• To distinguish ATF from gear oil in a pinch, remember ATF is a much thinner fluid and is usually colored red or green.
Gear oil basics:
• Gear oil works to lubricate and prevent corrosion in a manual transmission.
• Because manual transmissions experience high friction during gear changes and clutch
press-and-release, gear oil has additives of sulfur-bearing anti-wear compounds. This gives gear oil a distinctive, strong smell.
• Gear oil is also thicker than ATF because it serves mainly to lubricate the gearbox, transfer cases, and differentials.
Incorrectly using ATF in a manual transmission or gear oil in an automatic transmission can severely increase the wear and tear. ATF does not have the thick lubrication qualities needed in a manual gearbox, and gear oil does not contain all the additives needed to smoothly run an automatic transmission.
If you’re in need of a new or rebuilt transmission, contact Zumbrota Bearing and Gear. We stock a wide variety of manual transmission for immediate delivery, and if we don't have what you need on-hand, we'll find it!