Automatic Transmission Fluid (ATF) is known for its detergent properties. While primarily used in automatic transmissions, some mechanics use it to clean sludge and deposits from car engines. This process involves using ATF to flush the engine, removing built-up grime that can hinder performance. However, this practice is controversial and should be approached with caution.
One crucial step before an ATF flush is replacing the oil filter. A partially clogged filter can trap debris loosened by the ATF’s detergents, leading to complete blockage and activation of the bypass valve. This forces unfiltered oil through engine bearings, potentially causing significant damage. Similarly, old transmissions often fail after a fluid change because dislodged debris clogs the filter, reducing pressure and causing clutch slippage.
For a less aggressive cleaning, a small amount of ATF (about a quart) can be added to the engine oil and driven for a week. This allows the detergents to gradually clean the engine. A more intensive approach involves a 50/50 mix of ATF and oil, run for an hour before draining.
In a specific case, a Honda Accord V6 with a misfire had its cylinder deactivation pistons jammed and oil control solenoids clogged with sludge due to infrequent oil changes. After cleaning the components, a multi-stage ATF flush was performed: 100% ATF for an hour on a lift, a 50/50 mix driven for an hour, and a final oil change with new filters at each stage. This successfully restored the engine’s performance. The key takeaway is regular maintenance prevents sludge build-up, negating the need for risky procedures like ATF flushes.
Replacing the oil filter before an ATF engine cleaning is crucial to prevent clogging. A clogged filter can lead to unfiltered oil circulating through the engine, causing potential damage to bearings. Old transmissions without filter bypasses are particularly susceptible to failure after a fluid change due to debris clogging. A gradual cleaning with a small amount of ATF or a short-duration 50/50 mix can be less risky alternatives. Ultimately, regular oil changes are the best way to prevent sludge build-up and maintain engine health.
