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

Written by Charleen

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
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Engine Flush – Most Overlooked AMSOIL Product

Written by Ches Cain
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Product Overview: AMSOIL Engine Flush

One of my top sellers of course is the AMSOIL Engine Flush but when you take a look at the number of oil changes we sell really only about 15% are adding the flush to their order. In reality at least 75% of all the oil changes that are using AMSOIL for the first time with over 25,000 miles should use it.
Among the many reasons to use a walk-in customer had the following to say:
“My truck  (Ford F-150 non-ecoboost) was using about a quart of oil every 4000 miles or about at 3-months. I used the flush on the last oil change per your recommendation on using it to neutralize acids in order to help the oil’s detergent last longer and low and behold it also stopped from then on using oil!”
AMSOIL Engine Flush – Recommended for any engine with over 25,000 miles (Order FLSH-CN)
Well then this low cost product actually ensures our detergents will last longer by neutralizing the acids which are caused by deposits. It’s designed for all modern seals and gaskets. So it helps you get more out of the AMSOIL motor oils. The flush is also non-solvent based – Non-flammable meaning it’s not harsh on engines and contains nothing different that what is already in our oil – essentially a concentrated form of the detergents and depressants. That also makes it more environmental friendly. The flush helps reduce lifter noise, increases mileage by improving compression. Effectively addresses deposits around piston rings which rob power and cause blow-by. Helps the motor control temperatures. And as we learned – lessons blow-by aiding in better crankcase ventilation.
You want to take care of any deposits early and the volatility of non-synthetics or competitor’s synthetics which are likely to be of the Group III nature can potentially leave deposits in engines which run under severe service. In most applications you only need to use it once but on higher mileage engines which you may not know the history you may find two applications are necessary – meaning one at the time of each subsequent oil change. I can personally attest to that need in my 83 Eagle which was sludged up when I bought it. Slowly using our HDD 5W-30 (high detergent Heavy Duty Diesel & Gasoline Synthetic), flush and our bypass kit (BMK-21), I have improved mileage and oil consumption significantly.
Any car with more than 50,000 it’s a must. Customers do notice a difference. Use approximately one bottle for every 10 quarts of oil.
Amsoil Engine FlushAnd a note on the conditions which will create the need to flush – Sioux Falls winters especially – every time you cut that engine off and the crankcase drops below 60 degrees you are building up moisture in the crankcase. This eventually creates a condition resulting in wear is the motor is not warmed up properly but subsequently deposits as well so we urge you be aware of this and avoid running the engine for less than 10 minutes after the motor is fully warmed on days below 30 degrees. You need to get the moisture out of the crankcase as often as possible.
So if you are not interested in AMSOIL Synthetic Motor oils, still this makes a reason to visit our store. Our flush is unique – it’s not harsh like popular solvent based ones as it contains no flammables. It is mild enough to be used as a transmission flush as well and quite effective. Full instructions are located on the bottle.
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