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By Jay Hubbard, Automotive Collections Manager

Preservation Guidelines for Storage

Most collectors are familiar with the processes required for the care and cleaning of the exterior surface areas and the interiors of our treasures. I want to address the care and preservation of those less seen areas, the beating heart of our machines. Is there more to putting away an automobile than just shutting off the engine and walking away? If you’re not coming back to that car for a few months or even years, the answer is, yes, there is a lot more. Whether you’re placing the automobile on display or into off-site deep storage, the long-term preservation of the working parts begins as soon as you shut off the ignition, while the engine is still warm, and while its fluids are still in circulation.

Inspect the Automobile’s Engine Compartment and Undercarriage

Collected deposits of dirt, grease, oil splash and other debris are just as harmful underneath as they are on top. Deposits of dirt and desiccated grease will become places that moisture can collect and attack the metal parts those deposits cling to. Petroleum products can attack and dissolve rubber bushings, hoses, boots and seals. Fresh oil sprays and leaks are tomorrow’s greasy messes and today’s rubber destroyers. A thorough cleaning of the undercarriage and engine bay will slow the deterioration of so many components and make the automobile easier to maintain. After cleaning, remember to lubricate all of the joints and fittings to displace any cleaning fluids that may have found their way in.

The automobile engine is a violent environment of fire, poisonous gases and chemicals, as well as extreme temperatures; a crucible that creates corrosive chemicals that will damage the internal parts of the engine. We need to neutralize this environment before putting the engine away.

Start with the Cooling System

After a thorough draining and flushing of the system, then what? Refill it with a name brand antifreeze and water. The manufacturer of most of the name brand antifreezes will tell you that their product contains a rust inhibitor that will protect your engine. What most people don’t know is that without regular stirring and routine replacement, the rust inhibitor will settle and decay leaving your engine unprotected.

Let us consider the Wisconsin engine found in a Stutz automobile that is typical in construction to many engines built in the early 20th century. A beautiful thing, but note its construction. An aluminum crankcase, supporting iron cylinders, topped with brass water jacket covers, attached to an aluminum water manifold, all tied together with steel bolts. This mixture of dissimilar metals will lead to a condition called galvanic corrosion where the metals, when exposed to an electrolyte, will become a kind of battery, swapping electrons with one another until the sacrificial metal, in this case the aluminum, dissolves away. Even more modern engines will contain different amounts of these metals.

To combat this attack on the metals of your engine, we are going to eliminate the primary culprit, the electrolyte, water. The last coolant we will fill the system with is a 40:1 mixture of water and water soluble oil, which after circulation will be drained off following the last time you run the engine. Water soluble oil is easily obtained at your auto supply dealer or it can be purchased in bulk at most machine tool suppliers.

Lubrication System

For this, we are going to refer to Lycoming and Continental, makers of piston-driven aircraft engines and whose recommendations must stand up in the demanding world of powered flight. They recommend draining the engine oil, changing the oil filters and after the crankcase is refilled with fresh oil, running the engine for up to one hour or until the engine oil reaches a minimum temperature of 165 degrees Fahrenheit. This will insure that all of the internal parts of the engine are coated with a protective covering of oil.

During the last few minutes of this final engine run, you should be spraying either an engine fogging oil or pouring a cylinder oil into the carburetor until a thick oil smoke is visible from the exhaust pipe. This will coat the engine valve train and cylinders with a protective layer of oil. By now, the mixture water and water soluble oil has been well circulated.

After the Final Engine Shut Down and Before It Cools

Bags or containers of silica gel should be placed in the openings of the engine, inside the air filter housing or carburetor throat, the crankcase vents and the exhaust tail pipe after the engine is shut down and before it cools. These openings should then be sealed with either an aluminum duct tape or at the least tightly stuffed with a rag to reduce the amount of moisture entering the engine. Most of you are familiar with silica gel as it comes as a desiccant in many packaged items we receive in daily life. It has the characteristic of changing color as it absorbs moisture, making it easy to monitor, and can be dried in an oven for reuse when it is saturated. The degree and amount of the silica gel you use will depend upon the humidity of your storage environment.

Remove the Battery and Drain the Fuel

Remove the ignition battery or starting battery from the automobile and drain the fuel.

Common motor fuel is a volatile cocktail of many chemicals to comply with today’s environmental laws. Many of these chemicals can have damaging effects on your automobile if left to stand for long periods of time. Many repair shops will not guaranty repairs if the gasoline in the automobile is more than 90 days old. Remove the gasoline from any automobile that is going to sit and use it in some other engine, but do not store it. This is not only a safety issue but an issue to the maintenance of your automobiles.

Old gasoline will evaporate leaving behind a residue of a sticky glue‑like substance commonly known as varnish. This substance can cause engine valves to stick and bend push rods, carburetor valves to stick and jets to plug. Other chemicals in gasoline can attack the soft metals that make up many of the components of your fuel system. After the final shut down of the engine, drain all of the fuel from the fuel tank, open the carburetor to remove all of the fuel inside it, and blow out the fuel lines with air.

Whenever using motor fuel it is advisable to use a fuel stabilizer and a small amount of cylinder oil to preserve the fuel and lubricate the valves.

To prevent some of these fuel issues, many have gone to using non-ethanol blended fuel as this additive can be responsible for water absorption into your fuel and phase separation of the fuel itself. Ethanol can also be responsible for damage to the rubber parts of your fuel system. Non-ethanol fuel used to be available for marine use but is becoming harder to find. Another trick is to use aviation fuel (100 low lead) as a flushing agent during the last running of the engine. Aviation fuel has a much longer shelf life than regular motor fuel and contains fewer of the chemicals that give our older engines trouble. This will displace those last unreachable traces of motor fuel that are always left behind.

Remember that marine fuel and aviation fuel are not legal to use on the road as they are not taxed for road use.

Aircraft engine manufacturers recommend that the engine be parked in such a way as none of the cylinders are at top dead center and that the engine not be turned over again until you wish to place it back into service. Rotating the crankshaft will cause the protective coating of oil to be wiped off of cam lobes, lifters and cylinder walls.

Drain the Cooling System

Now it’s time to drain the water soluble oil mixture from the cooling system. While the engine is still warm, remove the upper and lower radiator hoses, and any thermostats and heater hoses, so the last of the water within the system can evaporate out leaving a coating of water soluble oil behind to protect the water jacket and lubricate the water pump.

Gear Boxes, Transmission and Differential.

The gear boxes, transmission and differential should be treated much the same way as the engine, though they are not subject to the internal pollution that internal combustion creates inside the engine. They can collect water and the lubricant can dry out over time as the lighter hydrocarbons evaporate. Open the lower drain plug on the gear box and inspect the fluid for water and consistency. Once satisfied with the contents of the gear box, make sure that it is properly filled with the correct lubricant and then seal the vents with silica gel as was done with the engine.

The aircraft industry has an aftermarket unit which, when plugged into the crankcase vents of our engine, will circulate air through the engine block, then through a container of silica gel (which will remove the water from the air) to maintain a dry environment within the engine. It is a rather expensive unit, but during my research I found plans for such a device that an individual made at home with an electrical outlet timer, an aquarium air pump, a two-liter soda bottle filled with silica gel, some plastic tubing and rubber stoppers. I believe an industrious person could expand this device to include not only the engine, but the gear boxes as well. These plans can be found online.


The clutch release linkage should be blocked open in such a way as to prevent the friction surface from remaining in contact with the flywheel or pressure plate. Leather face clutches should be saturated with Neatsfoot oil; other types should remain dry. Be certain which type you are dealing with. Leaving the clutch disengaged will prevent the friction disk from sticking to the flywheel or pressure plate and being damaged.


Since 1939, nearly all automobiles have been manufactured with hydraulically-actuated brakes. For automobiles built in the United States that means the use of DOT 3 brake fluid. If the brake system is working properly and not leaking, you may wish to simply flush out the old brake fluid with fresh DOT 3. But be warned, a characteristic of DOT 3 fluid is that it absorbs water. That water, once in the system, will cause corrosion in the brake lines and cylinders leading to future failure of the system. Another characteristic of DOT 3 is that it will remove any paint it comes in contact with, which means any leak can do a great deal of damage.

It is recommended that you consider replacing the brake fluid with DOT 5 fluid. DOT 5 does not absorb water and will not damage paint. It will require that the brake system be flushed with alcohol as the two fluids, DOT 3 and DOT 5, do not mix. This is best done as part of a complete hydraulic overhaul of the brake system. Something to consider.

Power Windows and Convertible Top Assemblies

All hydraulically-actuated power windows and convertible top assemblies built in the United States used DOT 3 fluid with the same ill effects. These systems should also be considered for a change of fluid as a leak in one of these can damage an automobile’s interior and its paint job. However, DOT 5 is not a suitable replacement for the fluid as it does not have the lubricating qualities necessary for the hydraulic pump that operates these systems. In these hydraulic systems, it has been recommended that ATF be used.


Where the automobile is to be stored will determine how the tires should be treated. If on public display, you may wish to leave the automobile on the ground for easy movement and a more natural appearance. From time to time, tires that are left supporting the automobile will have to be turned to prevent flat spots. Tires can be lifted and the automobile supported on jack stands. This presents a taller look to the car but saves on flat spots. Be sure to support the automobile under the axles or outer suspension points and use stands of a proper load rating.

In off-site storage, the automobile can be lifted and supported by jack stands under the axle and by the chassis to relieve the springs. Be certain to always support the axles, as most automobiles, particularly postwar two doors, are not designed to carry the weight of the axles hanging for prolonged periods. This can cause the automobile to bend, the doors to jam, and convertible tops to wrinkle. Tires should always be properly inflated so they maintain their shape and to prevent their inner tubes from collapsing.

Action Plan

You should have a plan and that plan will depend a lot on the overall condition of the automobile. Is it restored? To what degree is it restored? Has it been a Concours Queen? Or has it been on the road? Maybe it is a new acquisition in unknown condition. The overall condition of the automobile and its future use will determine how aggressive you will need to be in its deep freeze preparation. The basics are the same; the devil is in the details.

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