Engines Can Corrode While Doing Absolutely Nothing

Storage might seem like an easy life for an engine. There is no combustion pressure, no high temperature operation and no mechanical load. Unfortunately, an engine that is sitting still can develop a completely different set of problems.

Changes in ambient temperature can allow moisture to condense inside an engine. When that moisture reaches unprotected steel or iron surfaces, corrosion can begin forming on components such as cylinder walls, piston rings, bearings and other exposed metal surfaces.

An engine that remains unused for an extended period may also lose some of the protective oil film normally present during regular operation. When the engine is eventually started again, the first few moments of operation can occur before normal oil circulation has been fully re-established.

A Protective Oil Film Delivered by Aerosol

AMSOIL Engine Fogging Oil is supplied as an aerosol, allowing the product to be distributed into areas that would otherwise be difficult to coat evenly. Once applied, the volatile portion of the product dissipates and leaves behind a tenacious oil film containing corrosion protection.

That film retention is particularly valuable when equipment may sit unused for weeks or months. AMSOIL recommends Engine Fogging Oil for a broad range of two- and four-stroke equipment including motorcycles, ATVs, marine engines, lawn equipment, generators, cars and trucks.

The concept is particularly useful in engines where cylinder orientation or engine design can make conventional oil distribution during storage less effective. Outboard marine engines are one obvious example, but the underlying problem is not unique to marine equipment.

Classic Cars, Performance Engines and Race Cars Need Protection Too

Fogging oil is often marketed around seasonal equipment, but the same corrosion mechanisms apply to automotive engines.

A classic car or competition vehicle may spend considerably more time stationary than a normal daily driver. During that time, some valves may remain open, allowing humid outside air to reach internal engine surfaces through the intake or exhaust system. A car stored in a damp or poorly controlled garage can therefore remain exposed to moisture even though the vehicle itself never moves.

This was one of the applications discussed by AMSOIL's Len Groom in an EngineLabs technical feature examining the use of Engine Fogging Oil outside its more traditional small-engine and marine markets. Groom explained that although a race engine may not encounter the same environment as a personal watercraft, the materials being protected and the basic corrosion problem remain much the same.

Machine-Shop Equipment and Precision Metal Surfaces

The EngineLabs discussion uncovered another application that is easy to overlook: protecting exposed precision-machined workshop equipment.

Machine tools such as lathes and milling machines can have large areas of bare, accurately machined metal that must remain free of corrosion. Mill tables, milling vices and lathe ways are examples of surfaces where even light rust is undesirable, particularly in workshops exposed to high humidity.

EngineLabs asked Groom whether AMSOIL Engine Fogging Oil could be used for this purpose. His response was that it was particularly well suited to the application because it provides a light oily protective coating rather than the heavier wax-like film left by some long-term metal preservatives.

That distinction matters on precision machinery. A heavy storage coating can require considerable cleaning before the equipment is returned to use, whereas a light oil film can simply be wiped away where necessary.

Fogging Oil Isn't a Universal Workshop Spray

The unusual applications above do not mean Engine Fogging Oil should automatically replace every penetrating oil, assembly lubricant, cutting fluid or long-term metal preservative in the workshop.

Its strength is relatively specific: it is easy to apply, reaches difficult surfaces and leaves behind a persistent oily film designed to help protect metal from moisture and corrosion.

For internal engine storage, that is exactly the job it was designed to perform. For engine components awaiting assembly and certain precision-machined workshop surfaces, those same characteristics can also be useful.

For equipment-specific storage procedures, always follow the manufacturer's recommendations. Application methods also vary between engine types, particularly on modern engines fitted with sensitive intake sensors and other electronic components.

Rust Doesn't Care Whether the Engine Is Running

The expensive part of corrosion is rarely the visible patch of brown on a piece of metal. It is what that corrosion means when the affected surface is a cylinder bore, bearing journal, precision-machined engine component or machine-tool surface.

Engines and mechanical components can represent substantial investments in parts, machining and labour. Protecting those surfaces while equipment is inactive is considerably easier than repairing corrosion after it has occurred.

That is ultimately what makes fogging oil useful. It solves a fairly simple problem: when machinery stops moving, the protection still needs to remain behind.