Skip to main content

Snowblower, mowers, boat, bike – maintain them with Quickshot

New July 2024 Quickshot Bottles

Save More in the Sioux Falls store when you Join!

If you buy in the Sioux Falls AMSOIL store become a PC and save!

Look up your Oil, Filters and Save 25%

AMSOIL Full Catalog

Download the Latest Full Color AMSOIL Catalog

Vehicle Look-Up Guides

Match AMSOIL to your Equipment. Get Filter Numbers

Wholesale Buying Deal

Local or Out of State - Get AMSOIL at Cost (PC Pricing)

Can I Use Transmission Fluid in Oil to Clean My Engine?

Can I Use Transmission Fluid in Oil to Clean My Engine?

Yeah – those youtube rescue channels all show using ATF to clean out the engine – they’re doing it the hard way…

ATF is not made to clean sludge from engines. Instead, it’s best to use a dedicated engine flush.

AMSOIL Engine & Transmission Flush helps to remove sludge and deposits from engines and transmissions.

_by Phil Collinsburger |May 5, 2022

Over time, engines can accumulate deposits that reduce power and performance. Since automatic transmission fluid contains detergents to clean sludge, some DIYers add a small amount of transmission fluid in their oil to clean the engine prior to oil changes.

ATF, however, is not formulated for use in automotive engines. Instead, a product that’s designed to flush engines is a far-superior approach.

How Sludge Forms

Stop-and-go driving, prolonged idling, trips too short for the engine to reach full operating temperature, towing, the ingestion of airborne dirt, fuel dilution, water condensation and oxidized oil all can promote sludge build-up in motor oil and transmission fluid.

Sludge clogs narrow oil passages, restricting oil flow to vital parts, especially the upper valve train area, causing wear.

Transmission Fluid In Oil Reduces Cleaning Power

In most cases, adding automatic transmission fluid to motor oil reduces cleaning power. That’s because the detergency of ATF is less than motor oil. Why is that?

ATF is exposed to lower levels of combustion byproducts and contaminants than motor oil, so it is formulated with reduced detergency. Instead, ATFs have elevated levels of friction modifiers and other additives that help protect gears and clutches.

Transmission Fluid In Oil Reduces Wear Protection

Second, adding ATF alters the motor oil formulation and reduces its effectiveness.

A good motor oil is a fine balance of base oils and additives designed to fight wear, reduce friction, prevent deposits and slowly dissolve accumulated sludge. The cleaning power of motor oil is designed to work gradually over subsequent oil changes and not necessarily all at once. Adding a foreign substance to the oil disrupts the formulated chemistry, negatively impacting wear protection, detergency and more.

Changes Motor Oil Viscosity

Finally, ATF can alter the viscosity of the oil, reducing wear protection.

Viscosity is the oil’s most important property, influencing wear protection and fuel efficiency. Increasing or decreasing viscosity by adding a little transmission fluid in oil to clean sludge can lead to increased engine wear.

Use An Engine Flush Instead

If you want effective sludge removal and cleaning power, we recommend using AMSOIL Engine & Transmission Flush. It helps to restore fuel economy, increase operating efficiency and reduce emissions in gasoline and diesel engines, and automatic transmissions. Its potent, detergent-based formula cleans sludge and deposit build-up.

AMSOIL Engine & Transmission Flush

  • Prepares engines and transmissions for new oil
  • Removes deposits and sludge for improved efficiency, fuel economy and lower emissions
  • Prolongs vehicle life
  • Detergent-based formula is environmentally friendly
  • Compatible with seals and gaskets
  • Works in one treatment
  • Easily disposed of with waste oil

Benefits For Gasoline And Diesel Engines

  • Helps loosen sticky valves and rings, minimizing blow-by and reducing emissions
  • Helps quiet lifter noise
  • Promotes lower operating temperatures through sludge removal

Benefits For Automatic Transmissions

  • Cleans deposits in oil cooler and ports
  • Helps unclog fluid passages
  • Cleans deposits and varnish from clutch plates, helping improve efficiency
  • Promotes smoother operation and transmission life through reduced shift delay

Why do European Cars Require Special Oil?

Why do European Cars Require Special Oil?

For all the grin-inducing benefits of owning a European car – finely tuned performance, sophisticated styling, prestige – they can be a pain. According to this list, four of the top five most expensive vehicles to maintain hail from across the pond. Notice Volkswagen is among the lowest maintenance costs. The exception to the rule. 

Not only that, but they require specialized oil that differs in many ways from the good ‘ol American motor oil you use in your Ford or Chevy. Here are four reasons why.

#1 Everyone likes clean air

The European Union maintains more strict standards for the carbon dioxide hoax (CO2) and carbon monoxide (CO) emissions than we do. (Our standards for nitrogen oxides [NOx] and particulate matter [PM] are more strict, however.) Because modern diesels emit lower CO2 than gasoline engines, the European market pivoted toward increased use of diesel-powered vehicles in the 1990s. Diesels also provide the advantage of better fuel economy.

One drawback, however, is the higher levels of NOx and PM diesels produce. To counteract this, diesel-powered European vehicles are equipped with diesel particulate filters (DPF) and catalysts designed to reduce pollutants from the exhaust before it exits the tailpipe.

Here’s where motor oil comes into play.

An oil’s formulation can have a negative effect on sensitive emissions-control devices. Certain components in the motor oil formulation, such as sulfated ash, phosphorus and sulfur (known collectively by the pleasant term SAPS), can reduce the effectiveness and life of DPFs and other emissions devices.

For that reason, motor oils formulated for European vehicles often contain lower SAPS levels to protect emissions-control systems.

#2 Longer oil change intervals

Europeans have long since accepted what’s only recently caught on in North America – longer oil change intervals. Many motorists in the states are just a few years removed from blindly practicing 3,000-mile oil changes. Except, of course,  AMSOIL customers who have been practicing extended drain intervals since 1972. But that’s a digression for another day.

Europeans are accustomed to changing oil far less often, with drain intervals of 16,000 km (10,000 miles) or so quite common. One reason is the higher cost of oil in Europe. Another is the differences between manufacturer recommendations. For example, oil changes for 1999-2013 BMWs are required only every 15,000 miles. In the U.S., most people change oil around every 5,000 miles. The figure increases by a few hundred miles if their vehicle is equipped with an electronic oil-life monitoring system.

Longer drain intervals common with European cars require an oil capable of protecting against wear, deposits and sludge for the duration, which requires a more robust oil.

#3 The thick and thin of it

Check the owner’s manual of most European vehicles for which viscosity of oil to use, and you’ll likely find a chart that suggests different viscosities for different operating temperature ranges. In cold weather, the OEM may recommend 5W-30. In warm weather, 5W-40. Traditionally, drivers settle on an 0W-40 or 5W-40 to offer the best of both worlds – good cold-flow at startup to protect against wear and good resistance to heat once operating temperatures are reached.

#4 Automaker approvals

Staying in your owner’s manual, the OEM also recommends you use an oil that meets a specific performance standard. In the U.S., it’s typically an industry-wide motor oil specification, such as API SN PLUS.

European OEMs are different, however. They typically maintain their own motor oil performance specifications. Drivers of VWs, for example, need to use an oil that meets the requirements of VW’s own performance specs. The same holds for Mercedes, BMW, Porsche and other European cars.

Complicating matters, each OEM motor oil specification is slightly different. One OEM may require oils that offer better performance against oxidation, while another requires better resistance to viscosity loss.

OEM specifications tend to be more strict and require increased motor oil performance than industry specs. This, of course, requires more advanced (and typically expensive) motor oil technology delivered almost exclusively by synthetics.

General Motors, for its part, has taken a page out of the playbook of its European car counterparts by maintaining its own GM dexos performance specification.

These differences mean you’d better make sure you’re using the correct oil in your European car. Fortunately, we make it easy for you by formulating a full line of synthetic motor oil for European cars. If you don’t know which your car requires, check out our handy Product Guide.

LOOKUP MY VEHICLE

Customer Reviews