Engine Flush

Whenever the words ‘Engine Flush’ are uttered one can expect a certain amount of trepidation on the part of most technicians. They will likely recount horror stories about engine flushes that have gone terribly wrong, of resulting engine damage and why engine flushes should be avoided.

They were right to feel that way, as older methods of doing an engine flush was a high-risk gamble. You did an engine flush with the upmost care and only as a last resort, if the engine had been so horribly neglected that there was no other choice in the matter. Better to properly maintain your engine and use high-quality lubricants, as both will likely produce a long-lasting and problem-free engine over the lifetime of the vehicle.

That’s true. Proper engine maintenance and high-quality lubricants will maintain an engine. However, that does not mean the problems an engine flush addresses go away; or that an engine flush can be foregone entirely.

Age and Buildups

It would seem that with today’s long drain interval motor oils and advanced formulations the days of contaminate build-up in engines is a thing of the past. The reality is contaminate build-up still happens. It is a question of age and time, and what happens to motor oil over its lifetime circulating inside the engine. What vehicle owners have to remember are motor oils must accomplish certain key things: disperse heat, lubricate and keep the engine clean. Joe Price, brand marketing manager with Valvoline says over time motor oils will lose their ability to do these key things. As that happens, there is a build-up in contaminates that if left untreated will begin to impact engine performance and fuel efficiency.

“The build-up of deposits in the oil systems is a ‘natural’ process,” adds Steffen Niemietz, application engineer at Liqui Moly. “These deposits hamper the proper lubrication [of the engine] which leads to increased wear, increased fuel consumption and the risk of severely damaging the engine. This is similar to arteriosclerosis where narrowing of the blood vessels may lead to a heart attack.”

What an engine flush does is break down these deposits and allows them to be removed safely from the engine. The problem with earlier engine flush treatments was how they accomplished this process. Valvoline’s Price says much of the resistance to engine flushes was older treatments used solvents to remove contaminates from the engine’s interior. Those solvents proved to be a major problem.

First, solvents have a negative effect on elastomers which are used in the make-up of the seals within an engine. These seals are made to prevent fluids from leaking from major components into areas of the engine where they are not supposed to be. Solvents used in these early engine flush treatments had the unfortunate effect of reacting with the elastomers and reducing the elasticity of the seals which caused them to fail.

More problematic was how a solvent worked to remove contaminates.

Solvents worked by ‘stripping’ contaminates from the engine surfaces. To visualize this, think for a moment of how one goes about removing layers of paint or varnish from wood during a home renovation. One applies a chemical that slowly loosens those layers of paint and varnish so they can be taken off in long strips. Now imagine for a moment of those same long strips floating around inside an engine.

“Those large strips will then float through the engine system and potentially drop into the oil pan and then get sucked up into the oil pump and into the engine which then locks-up,” Price says.

It was this scenario that caused those hairs on the back of a technician’s neck to stand on end and why, for the longest time, engine flushes were avoided. The potential for engine damage was too great to contemplate for many.

New Detergents

So what has changed and why has engine flushing become something a technician should make part of a regular maintenance schedule? Contaminate build-up will happen over time and it will have to be addressed.

What has happened is that makers of engine flushing products have developed formulations that remove contaminate build-up without ‘stripping’ it off the walls of the engine. Instead, a complex blend of detergents now remove and breakdown contaminate build-up.

Valvoline’s Price says these new detergents provide a much safer way of eliminating contaminates from engines and avoid the problems ‘stripping’ while at the same time protecting the elastomers in engine seals. It is this kind of detergent mix which is found in the company’s newest Complete Oil System Cleaning Service product.

According to Valvoline, the cleaning solution breaks up, dissolves and then suspends sludge, deposits and varnish within 10 minutes of run time. The dispersant package keeps the particulates of sludge and deposits suspended in the solution and are evacuated through the drain plug port. These dispersants prevent residual particulates from accumulating at the bottom of the pan and then plugging up the pickup screen after the service is completed.

The additive package is held within a light base oil carrier. This light base oil adheres and protects the critical wear surfaces thereby eliminating any dry start concerns after the service.

Liqui Moly’s Engine Flush product, according to Niemietz, uses “concentrated detergents and dispersants to ‘solve’ the deposits and oil thinner to keep things flowing. Obviously, this combination is not meant to stay permanently in the oil. So Engine Flush must be applied immediately before the oil change. Pour it into the engine with the old oil and let the engine idle for a couple of minutes to allow the agents to take effect. Then the oil has to be drained, together with the ‘solved’ deposits. The fresh motor oil gets into a clean engine and can deliver its full performance. The formulation is optimized to remove the dirt – metaphorically speaking – layer by layer. This results in parts floating in the (old) oil, and there are no chunks able to clog anything.”

While there are no hard and fast rules as to when such an engine flush procedure should be used, Liqui Moly’s Niemietz suggests that it should be used every 60,000 kilometres and materials for Valvoline’s Complete Oil System Cleaner suggests a use every 15,000 miles as part of a regular maintenance schedule. Regardless of when a technician decides to use it, today’s engine flush should not cause one’s hair to stand on end at the back of the neck.