While researching motor oil requirements for old engines, I came across some manuals that show how little has changed over the years. Please notice how similar the1938 Dodge owner's manual is to the 1965 Valiant owner's manual.

1938 Dodge D-8 Owners Manual Recommendations

Draining the Crankcase and Crankcase Ventilation (Prolongs Engine Life)

Due to natural conditions in all automotive engines, the engine oil, in use, is constantly being impregnated with fuel, water, and acid, depreciating the the value of the oil as a lubricant. However, a ventilation system has been built into the engine in your car which expels a very large percentage of of these undesirable elements. With this ventilation, the frequency of draining the crankcase oil is also reduced, but nevertheless it is necessary to drain at the intervals specified.

Fuel accumulates in the engine oil because of certain excess of fuel in the combustion chambers not burning and working down the cylinder walls into the crankcase. Only certain percentages of vaporized fuel and air, when mixed, will ignited and explode in the combustion chamber. If the mixture contains too much fuel, the excess will not burn, some of it will remain on the cylinder walls and work down into the crankcase by the action of the pistons.

Water vapor is a product of combustion. There is approximately as much water vapor formed by weight as fuel consumed. Thais why you may notice white vapors and water coming out of the exhaust pipe, especially in cold weather. A certain amount of the vapor condenses on the cylinder walls and is also carried into the the crankcase by action of the pistons. A very large percentage of this water and fuel is carried out of the crankcase by means of the crankcase ventilation system.

Fresh air enters at the oil filler pipe which is capped with an air cleaner for catching dust and preventing it entering the crankcase. Due to the rotation of the crankshaft, the air and vapor in the crankcase is kept whirling. The vacuum created by the car running draws the air and vapor out of the crankcase through the ventilation outlet pipe at the rear of the engine.

This system of crankcase ventilation, as you can no doubt readily understand, reduces to a great extent a natural formation of sludge in the bottom of the crankcase. An excess amount of this sludge will interfere with proper engine lubrication.

Acid forms in the combustion chamber also due to natural causes in all automotive engines. Fuel contains varying percentages of sulphur and, when burned, changes to sulphur dioxide. The sulphur dioxide unites with water in the combustion chamber, making sulphurous acid.

These accumulated non-lubricating elements in the engine oil have damaging effects on the highly finished steel surfaces. Fuel thins the oil, reducing its lubricating ability. Water is a non-lubricant and is likely to freeze, causing stoppage of the oil circulation. The sulphurous acid attacks the highly finished steel surfaces and causes excessive wear. The rapidity of of accumulation of these elements increases as the temperature decreases. That is why it is recommended that the engine oil be drained more frequently in cold weather than in warm weather.

The best time to drain the crankcase is after a run and while the engine is still heated. The oil is thinner when it is hot and also thoroughly mixed. It will therefore carry off sediment more completely.

Kerosene should never be used for flushing out the oil pan and lubricating system. A certain amount will remain in the system, collecting in pockets from which it cannot readily be drained and will dilute the oil. For flushing, always use a good flushing oil.

Engine Oil Recommendations

Custom, in the past, was to use heavier (thicker) oils than at present. The use of light engine oil is an aid in cold weather starting, fuel economy, and the proper lubrication of parts.

To assist the selection of oil having the proper viscosity, select a recommended oil for the next lower minimum temperature point than the anticipated lowest temperature. During the winter, if there is any doubt as to the viscosity of oil to use, always select the grade with one lower viscosity number to insure ease of starting. During winter, all oils used should have a pour point or cold test below the lowest anticipated temperature that will be encountered during its use.

After the engine is broken in, oil changes should be made every 1500-2000 miles in winter and every 2500-3000 miles in summer.

When to Change the Engine Oil

In new cars, the oil should be drained out at about the first 500 miles of operation and refilled with an oil not heavier than No. 10-W during the winter, or heavier than SAE 20 or No. 20-W during the summer. The next oil change should be at 1500 miles speedometer reading and refilled with the viscosity of oil as recommended by the chart. After these initial changes of oil, if the driving conditions are normal, oil changes should be made every 1500 to 2000 miles in the winter and every 2500 to 3000 miles in summer.

It is always advisable to drain the crankcase while the engine is at normal operating temperature. Oil will drain more completely when hot, and will, therefore, carry more of the foreign material and dirt with it if drained while the engine is warm.

Dust Roads and Dust Storms

Driving over dusty roads or through dust storms introduces abrasive material into the engine. Air cleaners which are kept in good clean condition decrease the amount of dust that may enter the crankcase. However, if the oil become contaminated with dust or dirt, it should be drained promptly to prevent harmful engine wear. The frequency of draining depends upon the severity of the dust conditions and no definite draining periods can be recommended. It should be remembered that an oil change to eliminate abrasive dust may be considerably cheaper than to take a chance on worn engine parts.

Winter Driving

During winter, if the car is driven for short distances of only a few miles at a time, water will condense in the crankcase and form a sludge which may freeze and clog the oil inlet screen. This is especially true if winter temperatures are extremely low for an extended period of time. Under conditions of this kind, the engine does not become sufficiently warm to expel the water through the crankcase ventilation system, and the oil should , therefore, be changed about every 500 miles, and under extreme conditions, less than 500 miles, to eliminate sludge. The engine should be thoroughly warm before it is drained.

As an alternative to this frequent change period during winter, an occasional drive of 30 miles or more at speeds of 50 miles per hour or higher, will do much to eliminate the water through the crankcase ventilation system and the change period may be extended to 1000 miles, or the normally recommended 1500 miles winter change if these longer drives are indulged in frequently.

The Oil Filter

The function of the oil filter is to remove dirt and foreign material from the oil in order to assist in keeping the oil clean. This is a continuous process, and the filter cartridge will continue to trap dirt until it becomes clogged. Due to the manner of connecting the oil filter to the oiling system, clogging of the filter will not stop the circulation of oil to the bearings. However, when the oil filter is clogged, it ceases to filter the oil. It is, therefore, advisable to install a new oil filter every 8000 miles. In dusty areas, it may be advisable to examine the oil and change filters more frequently, or at any time when the oil appears to be excessively dirty.

1936-1942 Plymouth Service Manual Recommendations

Engine Oil Recommendations

1. The recommendations shown on the "Table of Capacities, Frequencies, and Lubricants" are based on the principle that lower viscosity oils circulate more rapidly and lubricate parts with closer clearances more readily than heavier oils. Complete satisfaction, however, depends upon the use of only well refined high quality products.
2. For cars of comparatively low mileage, SAE 20 or No. 20-W Engine Oil is recommended as a general summer oil. Either grade may be used in tropical climates during the winter months or No. 20-W Engine Oil may be used in localities where only very mild winter conditions prevail, such as territories where temperatures never go below 10°F above zero. If, however, as a result of continued high speed driving or other causes, oil consumption becomes a factor, SAE 30 Engine Oil may be used for temperatures above 32°F above zero.
3. No. 10-W Engine Oil is recommended as a general winter oil for temperatures as low as 10°F below zero, but no lower. However, should atmospheric temperatures rise above +32°F during winter, No. 10-W is satisfactory, and a change is not necessary until the next mileage period. No. 10-W Engine Oil may also be used during summer, if desired provided driving habits are moderate.
4. For sub-zero winter conditions, such as in temperatures below -10°F, No. 10-W Engine Oil should be diluted with 10% colorless, refined kerosene, which should be thoroughly mixed with the oil before it is added to the engine.

When to Change Engine Oil

1. Oil changes should be made, under normal conditions, every 1500 to 2000 miles during winter and every 2500 to 3000 miles during summer. It is always advisable to drain the oil while the engine is at normal operating temperature, because the oil will drain more completely when hot, carrying more of the foreign material and dirt with it.
2. During the winter, the engine oil should have a pour point or cold test below the lowest temperature that will be encountered during its use. If the car is driven for short distances of only a few miles at a time, moisture in the crankcase will condense and form a sludge which may freeze and clog the oil inlet screen. This condition is greatly aggravated by extremely low temperatures extending for a long period of time. Under driving conditions of this type, the engine does not become sufficiently warm to expel the moisture through the crankcase ventilator. Therefore, under these conditions, the oil should be changed every 500 miles to eliminate sludge.
3. An alternative to this frequent change period during the winter in an occasional drive of 30 miles or more which will help to eliminate water accumulation through the crankcase ventilation system. If the car is driven in this manner frequently, the oil may be changed at the normal recommended winter change period of 1500 to 2000 miles.

Replacement of Oil Filter

Install a new oil filter, a new oil filter cartridge (if equipped with the replaceable cartridge type) every 8000 miles. In dusty areas, it may be advisable to change filter, or cartridge, at any time when the oil appears excessively dirty.

1964 & 1965 Valiant Owner's Manual Recommendations

Engine Oil Recommendations

The engine of your car is made with parts fitted to close limits. These parts are finished to such a smooth surface that that there is actually no wearing-in process and the original clearance between the moving parts remains more constant. For this reason, light body oils of the consistency recommended in the chart should be used for lubrication.

As the car owner must necessary be responsible for the lubrication of his car and the selection of lubricants, the choice of engine oil is of major importance. Based upon the lubrication recommendations, CHRYCO SUPER MOTOR OIL, or an oil of known quality from a reputable oil refiner or distributor should be used. The type of service for which an engine oil is intended is usually designated MS, MM, or ML on the container. These service classification have been established by the API (American Petroleum Institute). This classification does not replace the SAE rating for grade of weight of the oil. The "oil recommendation chart" indicates the weight of body of the oil recommended for the various temperature ranges. When oil is selected that has been labeled by the refiner, with more than one SAE rating (multipurpose oil), the container designation should include the SAE recommendation for the anticipated temperature range.

For best results and engine protection , the car owner should select: (1) an oil that conforms to the requirement of API classification "for service MS" (2) an oil of proper viscosity, SAE number for the anticipated temperature range as shown in the "oil recommendation chart".

Oils that do not have an SAE designation and an "MS" classification on the container should not be used . Straight Mineral Oil should never be used.

When to Change the Engine Oil

The optimum engine oil change period will vary widely depending upon the type of operation, weather conditions, and other operating variables. For instance, during short trip driving in cold weather or driving on dusty roads, oil changes should be made as frequently as every 500 miles. Cross-country driving with good oils will permit 4,000 miles of operation between changes. As a general rule, however, it is recommended that the engine oil be changed approximately every three month (or 4,000 miles, whichever occurs first). We suggest that you consult with your dealer to determine the oil change period required to meet your special operating conditions.

The oil added to the engine at the factory is a high quality oil "For Service MS". It should be drained in accordance with the type of service in which your car is used as described above - after approximately 3 months (or 4,000 miles, whichever occurs first) of city traffic operation.

Severe service, such as taxi and police driving, which is principally short trip operation, including frequent and prolonged idling, requires more frequent oil changes. For this type of service, the engine oil should be changed every 2,000 miles, with filter changed at least every second oil change. It is not necessary to add any materials to crankcase oils for most types of service. In some instances, where a car is operated infrequently or for short trips continuously, rust may form in the engine. CHRYCO ENGINE OIL SUPPLEMENT contains an anti-rust material to prevent this occurrence. It also has anti-scuff properties and should be used during the break-in period following a major engine overhaul.

New engines frequently consume some oil during their early life. This is a normal part of the break-in process and should not be interpreted as an indication of difficulty. If it is necessary to add oil during this initial period, an oil "For Service MS" of the proper viscosity grade should be used. Nondetergent or straight mineral oils must never be used.

IMPORTANT: During winter, all oils used should have a pour point or cold test below the lowest anticipated temperature that will be encountered during its use.

It is always advisable to drain the crankcase while the engine is at normal operating temperature. Oil will drain more completely when hot, and will, therefore, carry more of the foreign material and dirt with it if drained while the engine is warm.

Dust Roads and Dust Storms

Driving over dusty roads or through dust storms introduces abrasive material into the engine. Air cleaners which are kept in good clean condition decrease the amount of dust that may enter the crankcase. However, if the oil become contaminated with dust or dirt, it should be drained promptly to prevent harmful engine wear. The frequency of draining depends upon the severity of the dust conditions and no definite draining periods can be recommended. It should be remembered that an oil change to eliminate abrasive dust may be considerably cheaper than to take a chance on worn engine parts.

Winter Driving

During winter, if the car is driven for short distances of only a few miles at a time, moisture will condense in the crankcase and form a sludge which may freeze and clog the oil inlet screen. This is especially true if winter temperatures are extremely low for an extended period of time. Under conditions of this kind, the engine does not become sufficiently warm to expel the water through the crankcase ventilation system, and the oil should , therefore, be changed about every 500 miles and under extreme conditions, less than 500 miles, to eliminate sludge. The engine should be thoroughly warm before it is drained.

As an alternative to this frequent change period during winter, an occasional drive of 30 miles or more at speeds of 50 miles per hour or higher, will do much to eliminate the water through the crankcase ventilation system and the change period may be extended, if these longer drives are indulged in frequently.

If the engine is, to quite an extent, operated in unusually low temperatures, or on short runs where normal engine operating temperatures are not shown by the heat indicator, it is advisable to cover part of the area of the radiator grille with a grille cover.

The Oil Filter

The function of the oil filter is to remove dirt and foreign material from the oil in order to assist in keeping the oil clean. This is a continuous process, and the filter cartridge will continue to trap dirt until it becomes clogged. Due to the manner of connecting the oil filter to the oiling system, clogging of the filter will not stop the circulation of oil to the bearings. However, when the oil filter is clogged, it ceases to filter the oil. It is, therefore, advisable to install a new oil filter at the intervals specified in the Maintenance Schedule. In dusty areas, it may be advisable to examine the oil and change filters more frequently, or at any time when the oil appears to be excessively dirty.

Engine Oil Dilution

Due to natural conditions in all automotive engines, the engine oil, in use, is constantly being impregnated with fuel, water and acid, depreciating the value of the oil as a lubricant. However, a ventilating system has been built into the engine in your car which expels a very large percentage of these undesirable elements. With this ventilation, the frequency of draining the crankcase oil is also reduced, but nevertheless it is advisable to drain at the intervals specified.

Fuel accumulates in the engine oil because of certain excess of fuel in the combustion chambers not burning and working down the cylinder walls into the crankcase. Only certain percentages of of vaporized fuel and air, when mixed, will ignite and explode in the combustion chamber. If the mixture contains too much fuel, the excess fuel will not burn, some of it will remain on the cylinder walls and work down into the crankcase by the action of the pistons.

Water vapor is product of combustion. There is approximately as much water vapor formed by weight as fuel consumed. That is why you may notice white vapor and water coming out of the exhaust pipe, especially in cold weather.

A certain amount of this vapor condenses on the cylinder walls and is also carried into the crankcase by action of the pistons. A very large percentage of this water and fuel is carried out of the crankcase by means of the crankcase ventilation system.

Fresh air enters at the oil filler pipe which is capped with an air cleaner for catching dust dust and preventing it entering the crankcase. Due to the rotation of the crankshaft, the air and vapor in the crankcase are kept whirling. This air is drawn out of the cylinder head cover by manifold vacuum in to the combustion chamber and dispelled with the exhaust gases.

This system of crankcase ventilation, as you can no doubt readily understand, reduces to a great extent the a natural formation of sludge in the bottom of the crankcase. An excess amount of this sludge will interfere with proper engine lubrication.

Acid forms in the combustion chamber also due to natural causes in all automotive engines. fuel contains varying percentages of sulphur and, when burned, changes to sulphur dioxide. The sulphur dioxide unites with water in the combustion chamber, making sulphurous acid.

These accumulated non-lubricating elements in the engine oil have damaging effects on the highly finished steel surfaces. Fuel thins the oil, reducing its lubricating ability. Water is a non-lubricant and is likely to freeze, causing stoppage of the oil circulation. The sulphurous acid attacks highly finished surfaces and causes excessive wear. The rapidity of accumulation of these elements increases as the temperature decreases. That is why it is recommended that the engine oil be drained more frequently in cold weather than in warm weather.

The best time to drain the crankcase is after a run and while the engine is still heated. The oil is thinner when it is hot an also thoroughly mixed. It will therefore carry off sediment more completely.

Kerosene should never be used for flushing out the oil pan an lubricating system. A certain amount will remain in the system, collecting in pockets from which it cannot readily be drained and will dilute the oil.

1975 Chrysler Service Manual Recomendations

Oil Viscosity Recommendations

Where temperatures are consistently above +32°F

• SAE 10W-30
• SAE 10W-40
• SAE 10W-50
• SAE 20W-40
• SAE 20W-50

Suitable for year-long operation in many parts of the USA; may be used where temperatures occasionally drop as low as -10°F

• SAE 5W-40
• SAE 10W-30
• SAE 10W-40
• SAE 10W-50

Recommended where minimum temperatures are consistently below +10°F

• SAE 5W-20
• SAE 5W-30
• SAE 5W-40

Single Grades

• SAE 30 - Where temperatures are consistently above +32°F
• SAE 10W - Where temperatures range between +32°F and -10°F

When outside temperatures are consistently below 32°F, SAE 10W-30 or SAE 10W-40 are recommended for ease in cold starting. As stated in the above table, oils of the SAE 5W-20 grade number may be used when minimum temperatures consistently fall below +10°F. However, even in cold weather, these grades should not be used if the vehicle is driven in competition or other forms of maximum performance operation.

Vehicles Equipped With High Performance V-8 Engines

If the vehicle is to be used for maximum performance service (very high speed or very rapid acceleration), the engine requires heavier than normal lubricating oil. This is due to the high speeds, loads, and temperature of the moving parts developed in these engines during this type of operation.

For best protection of engine under these conditions, the heaviest oil of SE quality should be used that will permit satisfactory cold starting. SAE 30 and SAE 40 are recommended. Multi-viscosity oils SAE 20W-40 and SAE 20W-50 may also be used.