Volkswagen Air Cooled 1949-1969 Repair Guide

Engine Oil



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Fig. Fig. 1 A green or red light glows on the speedometer gauge when oil pressure is too low. When the oil pressure is great enough, the diaphragm moves enough to break the warning light circuit and the light goes out

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Fig. Fig. 2 All engines covered by this guide utilize a single pressure relief oil system (as shown)

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Fig. Fig. 3 When the engine is cold, oil pressure is high. Flowing oil forces the pressure relief valve down and goes directly to the lubrication points along the main gallery

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Fig. Fig. 4 As the engine warms up, oil pressure exerts less force on the relief valve. Some of the oil flows to the lubrication points, while the rest flows to the oil cooler

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Fig. Fig. 5 Once the engine is hot, the oil cannot produce enough pressure to depress the relief valve-therefore, all of the oil flows through the oil cooler

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Fig. Fig. 6 In 1970, Volkswagen introduced a dual pressure relief oil system on all of their 1600 engines

The flow diagram represents the flow of lubricating oil through the Volkswagen engine. After being sucked up through the suction tube at the bottom of the crankcase, oil flows through the oil pump to either the oil cooler or the oil pressure relief valve, depending on whether the oil is under high or low pressure. When the engine is cold, and the oil thick, the oil cooler is bypassed and the cold, high pressure, oil flows through the relief valve to the engine passageways. However, when the engine is warm and the oil thinner, oil travels through the oil cooler, which is directly in the path of the cooling air from the cooling fan. In this way, the oil is able to act as an even greater medium of engine cooling. After leaving the cooler or relief valve, the engine oil makes its way to critical lubrication points in the Volkswagen powerplant. The first route is to the crankshaft main bearings, where the oil is transferred to the crankshaft by means of drilled passageways. From the crankshaft, oil then flows to the connecting rod bearings, and is splashed onto the cylinder walls, pistons and piston rings. The force of oil hurled from the rotating parts to the cylinder walls is considerable. It is for this reason that the oil does a proper job of lubricating the cylinder walls and pistons.

A second route of the engine oil is to the camshaft bearings, while a third is through the hollow pushrods to the rocker arm bearings and the valve stems.

The Volkswagen engine uses a gear type pump. In this method, two gears are enclosed in a snug housing-the driven gear and the idler gear. The driven gear is turned by the camshaft, and the idler gear is mounted to turn freely on a stub shaft. The turning of the gears creates the oil-pumping action. The pump creates considerable suction at the suction pipe located inside the wire mesh oil strainer at the bottom of the crankcase.


The theory involved in the lubrication of any internal combustion engine is to place a substance between two objects in relative motion so as to lessen friction and make their movement easier. The substance must be both adhesive and cohesive-adhesive so that it clings to each of the moving surfaces, cohesive so that it does not separate and be driven out of the space it must occupy. An engine which would last practically forever would be possible if a lubricant could be found which would fully separate all moving surfaces so that there would be no contact whatsoever between them. Full lubrication is the goal of all engine lubrication systems, and the choice of the proper type and weight of engine oil can mean a great deal. In addition to reducing friction between moving parts, the oil in the Volkswagen engine also serves the following purposes: (1) it dissipates heat and helps parts to run more coolly, especially with the help of the oil cooler; (2) it acts as a seal for the pistons, rings, and cylinder walls; (3) it helps to reduce engine noises; (4) it helps to keep surfaces from rusting or corroding; (5) it acts as a cleaning agent, especially if it is of the high-detergent type commonly used today; (6) it removes foreign substances with the help of the wire mesh oil strainer.

Types of Engine Oil

In addition to detergent versus nondetergent oils, there are three major categories of oil designed for use in automobile engines. The following classifications have been set up by the American Petroleum Institute:

Service MS (Severe). When the letters MS appear on an oil container, they mean that the oil is refined and reinforced with additives so that it will satisfy the most severe demands made on it by a gasoline engine. Service MS oils are able to stand up to the especially hard demands imposed by start-stop driving in which condensation tends to build up on cylinder walls and in the crankcase. It is in this type of service that crankcase dilution takes place most readily and sludge and varnish are most rapidly formed. Therefore, if you drive your Volkswagen at low speeds and for short distances (and, of course, at turnpike speeds), you should especially be sure that the crankcase contains oil meeting the MS classification requirements.

Service MM (Medium). This classification indicates that the oil is meant for engines that receive only moderate demands and service. This type of oil is not recommended for the Volkswagen unless it also exceeds the requirements of the MS class. Engines using oil for service MM are generally not called upon to perform under severe conditions for any significant length of time, although there may be brief periods of severe operation.

Service ML (Light). This oil is designed for use in engines operating under light and favorable conditions, and which present no problems in the way of sludge deposits, bearing corrosion, or otherwise have no special requirements.

Only oils displaying the ratings HD (high-detergency) and MS (motor severe) should be used in the Volkswagen engine. Ratings exceeded by the engine oil must include these two classifications.

On some early engines (prior to 1954), a fiber camshaft timing gear was used. High-detergency oil is not recommended for these engines.

In 1970, new categories were set up for oil designations by the American Petroleum Institute. The new designations replaced the old. The new designations are:

SD. This type oil is required for warranty service on 1968 and later gasoline engines. It resists formation of deposits at both high and low temperatures and prevents rust and corrosion.

SC. This is the minimum requirement for 1964-67 automobiles and light trucks. It is also rust and corrosion resistant.

SB. SB oil is suitable for light duty engine operation only. This is not to be used in any Volkswagen or other air cooled engine.

SA. SA should be used for mild duty only. It has no special protection capabilities. This oil is not to be used in any Volkswagen or other air cooled engine.

Viscosity Requirements

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Fig. Fig. 7 Make sure to add the proper viscosity oil to your engine, depending on the temperature range expected until the next oil change

In addition to meeting the HD and MS classifications of the American Petroleum Institute, oils for the Volkswagen engine must also be of a certain viscosity, depending upon the outside temperature in which the car is operated. Viscosity is defined as resistance to flow, and oils with higher viscosity numbers (e.g. 30) are thicker than those of lower viscosity numbers (e.g. 10W). The "W" after the lower viscosity indices means that the oils are desirable for use in cold weather or winter periods.

SAE viscosity ratings presently run from 5 to 50, and reflect the flow ability of the oil at a definite temperature. It is most important that the correct viscosity oil be used in the Volkswagen engine. If the viscosity is too low, moving parts will tend to come into contact, thereby causing high friction and wear, and possible bearing failures. Just as oils must be able to separate moving parts properly, they must be thin enough to get between the parts in the first place. If an oil is too thick it will not be able to flow properly into tight and critical bearing areas, with the result that incomplete separation of moving parts leads to bearing failure or a high rate of wear. If an oil is either too thick or too thin it cannot provide full lubrication and separation of close-tolerance moving parts in the engine. In order to underscore the importance of the proper engine oil, consider the following example: the Volkswagen Squareback Sedan, while cruising at 70 miles per hour, will have its engine turning at approximately 3,000 revolutions per minute. This means that the crankshaft will turn 3,000 times each minute. Each point on the crankshaft number one main bearing surface is traveling in the same 2.16 in. circle at a frequency of 58 times each second! The engine oil has only 0.00033 second to get from the main bearing drilling into the crankshaft drilling; obviously not time enough for oil that flows too slowly. At this same time, the four pistons are sliding along the cylinder walls at a speed of 18 miles per hour. The choice of engine oil can mean the difference between sliding, gliding, rubbing, or galling in all of these parts. With the closely-machined surfaces and clearances in the Volkswagen engine, it is important that lubricating oil be of such a weight that it can separate moving parts effectively and still be able to flow at the proper rate. For maximum engine life and efficiency, the Volkswagen factory recommends the following selection process in choosing the oil for your car:


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Fig. Fig. 8 The oil dipstick (arrow) is located near the right-hand side of the crankshaft pulley

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Fig. Fig. 9 The oil dipstick on older models is mounted in the same position as on newer engines

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Fig. Fig. 10 The oil level in the engine should fall between the two marks

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Fig. Fig. 11 Remove the oil fill cap ...

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Fig. Fig. 12 ... then fill the engine with the proper type and amount of clean engine oil

To check the engine oil level, park the car on level ground and wait 5 minutes to allow all the oil in the engine to drain into the crankcase.

Check the oil level by withdrawing the dipstick and wiping it clean. Insert the dipstick into its hole and note the position of the oil level on the bottom of the stick. The level should be between the two marks on the bottom of the stick, preferably closer to the top mark. The distance between the two marks represents one quart of oil.

On upright fan engines, the dipstick is located directly beneath the generator; oil is added through the capped opening beside the generator support post. On the type 3 the dipstick and filler are located in the lower door jamb of the rear compartment lid.


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Fig. Fig. 13 Exploded view of the oil strainer mounting on all engines

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Fig. Fig. 14 After raising and safely supporting the vehicle, loosen and remove the oil drain plug ...

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Fig. Fig. 15 ... and allow the oil to drain into an aptly-sized catch pan

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Fig. Fig. 16 To clean the oil strainer, remove the 6 capnuts ...

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Fig. Fig. 17 ... then remove the strainer plate from the crankcase

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Fig. Fig. 18 Make certain to thoroughly clean off all dirt and grime, as seen on this oil strainer plate (arrow)

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Fig. Fig. 19 Remove the lower oil strainer gasket ...

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Fig. Fig. 20 ... pull the oil strainer out of its hole ...

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Fig. Fig. 21 ... then remove the upper oil strainer gasket from the crankcase

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Fig. Fig. 22 When installing the cover plate, make sure to tighten the cap nuts in the sequence shown

The engine oil should be changed only after the engine has been warmed up to operating temperature. In this way, the oil holds in suspension many of the contaminants that would otherwise remain in the engine. As the oil drains, it carries dirt and sludge from the engine. After the initial oil change at 600 miles, the oil should be changed regularly at a period not to exceed 3,000 miles. If a Volkswagen is being operated mainly for short, slow-speed trips it may be advisable to change oil more often, say 1,500 or 2,000 miles, especially if cold temperatures prevail. In arctic climates, it is recommended that engine oil be changed every 750 miles.

When changing the oil, first unscrew the drain plug in the center of the crankcase and allow the dirty oil to drain into a suitable receptacle. During every oil change, the oil strainer should also be cleaned. This wire mesh strainer is held in place by six cap nuts, and should be cleaned thoroughly with a safe solvent. The strainer plate should also be cleaned. This lowest part of the crankcase collects a great deal of sludge in the course of 3,000 miles. Install the assembly, using new gaskets (2) and the copper washers on the cap nuts in order to prevent leaking at the strainer plate. Before refilling the engine with oil, install the drain plug and tighten to a torque not to exceed 22 ft. lbs. (3mkg).

The proper amount of oil to put into the crankcase of any Volkswagen is 5.3 U.S. pints (2.5 liters). This quantity should be measured, possibly through use of a pint jar. Under no circumstances should a full 3 quarts be put into the engine. Overfilling will probably result in failure of various engine oil seals and severe leakage. It is not harmful if, upon refilling with this quantity, the oil level is either a few millimeters above or below the full mark on the dipstick. As long as the oil level is between the two marks, there is no danger of the oil level being too low. However, should the level fall below the lower mark at any time, approximately one quart should be added to the crankcase as soon as possible to assure proper lubrication.

It is recommended that the Volkswagen owner stay with the same brand of oil, because mixing different types of oils could possibly be detrimental to proper lubrication of the engine. If a Volkswagen has been run for many thousands of miles on a non-detergent oil (not recommended), it is advisable to be careful in switching to a high-detergency brand. When such a change is made, it is possible that the detergent oil will do its cleaning job too well, and clog up narrow oil passages with dirt or other foreign matter that has accumulated over the miles.

After the oil has been changed, the air cleaner should be inspected for possible cleaning and/or topping up with fresh oil. The refill requirement for the oil bath air cleaner is given in the Capacities and Pressures Chart. It is a welcome convenience that the total of the crankcase requirement and the oil cleaner requirement is approximately three quarts. In this way, there is no leftover or wasted oil. The air cleaner oil bath uses the same oil.