How to change an Oil Filter on a Classic Car

How to change an Oil Filter on a Classic Car

This guide captures ‘bygone’ advice on how to change an oil filter on a Classic Car. It is part of a series I am building that describes what to do on a Classic Car Basic Service.

Useful information for Classic Car and Retro Car enthusiasts, as many of these tasks are no longer required on modern day cars.

Remember folks these are ‘bygone guides’ … useful but the safety and personal protective equipment measures are reflective of bygone awareness. Stay safe.





What are Oil Filters for on a Classic Car

Oil filters are needed because of the contamination caused by normal combustion in the engine.

For each litre of petrol used, slightly more than a litre of water is formed. While most of this is blown away by the exhaust some remains in the engine and finds its way down into the sump to contaminate the oil.

Carbon, sludge and other semi-solid impurities also find their way into the oil, some of which combine with the water traces to form more sludge.

All these contaminants can have a harmful effect.

If for example an oilway in the crankshaft becomes blocked by sludge a big end or main bearing could be deprived of lubricant.

This could lead to the disinte­gration of the bearing itself and lead quickly to major damage to the crankshaft.


How many Oil Filters are there on a Classic Car

Typically there are two oil filters on a Classic Car. Both are provided to remove the above impurities. One which protects the oil pump itself from largish pieces of rubbish. This is is an integral part of the engine and is serviced only if the engine is dismantled.

The other filter deals with the finer contaminants. If it becomes choked to the point where oil cannot pass through it an automatic bypass valve cuts in which allows the full flow of oil to be maintained. But this oil is unfiltered and carries all the undesirable elements with it.


When to change the Oil Filter on a Classic Car

This filter is changed regularly as part of the normal change of engine oil.

The owner’s manual for your car will say whether the filter should be replaced at every oil change, or at every other oil change.

If there is any doubt it is best to play for safety and renew the filter at every oil change. This applies especially to cars with a low annual mileage. Say 10,000 km (6,000 miles) or less-since their engines are more likely to suffer from contamination than cars used every day over longish distances.


Different types of Oil Filter on a Classic Car

Oil filters come in two main types. The screw-in pattern and the replaceable element type contained in a tubular shell. Below is advice on how to change both.


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How to change a Screw-in Oil Filter on a Classic Car

An oil filter of the screw-in type is usually about 7.5 cm (3in.) in diameter and is fitted to the side of the engine near the bottom.

As a rule removing it involves no more than grasping it firmly with one hand and unscrewing it from the engine.

But if it will not budge first make sure you are turning it the right way. Anticlockwise and then try using an old glove for a better grip.

If it still will not budge then some gentle if not so gentle persuasion is needed.

How to remove a stuck Oil Filter on a Classic Car

The following is classic ‘bygone advice’ yet is followed by a more modern day solution.

Find a stout iron rod, a poker is ideal, and a couple of feet or so of old fashioned clothes line (not the plastic type) or a similar thin rope. Tie one end of the rope tightly to the end of the poker. Rest the poker against the side of the filter unit and pass the line right round the filter to join the poker again.

Lash it so that the line grips the filter tightly and use the poker as a lever to start the unit turning.

If this still does not work, you could buy a filter wrench, or take the whole housing off the car so you can wrestle off the filter in a bench vice.

What you must not do is to try to bang the filter round with a hammer and cold chisel, because the stub might snap, leaving you with part of the stub locked into the cylinder block.

How to change an Oil Filter on a Classic Car
Oil filters of the screw-in type sometimes stick fast because heat expands the gasket. A filter wrench is one way to move them

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How to change a Screw-In Oil Filter on a Classic Car
Alternatively, drive a screwdriver right through the filter body and use it as a lever. Take care not to shear off the filter base

With the old filter off all that is needed is to remove the sealing washer, clean the face of the cylinder block where the washer was and tightly screw in a new filter.

Prepare the oil filter mounting on a Classic Car
Prepare the oil filter mounting on a Classic Car

If the old sealing washer is damaged in any way fit a new one, lightly greased.

A new gasket usually comes with the new filter; if not, buy one of the correct size. Oil the gasket lightly before reassembly
A new gasket usually comes with the new filter; if not, buy one of the correct size. Oil the gasket lightly before reassembly
Finally, screw the new filter in place. It should be hand-tight only, but run the engine to ensure there are no leaks
Finally, screw the new filter in place. It should be hand-tight only, but run the engine to ensure there are no leaks




How to change a Cartridge Type Oil Filter on a Classic Car

Replacing a filter of the cartridge type presents no physical difficulties.

The main thing to guard against is losing components as you remove the filter canister so keep a biscuit tin or similar container handy.

You will also need a new sealing ring. So if there is not one in the filter element box when you buy it then buy one separately.

A large bolt holds the canister in place. With the bolt removed either the canister will fall away from its mounting or a little ‘wiggling’ may be needed.

How to Change a Cartridge Type Oil  on a Classic Car
Cartridge-type oil filters normally need to be removed from below the car. First unscrew the large cover retaining bolt

If the sealing ring between the canister and mounting does not come away by itself pry it loose with a small screw­driver. The filter element is inside the canister and is simply shaken out into the biscuit tin.

Still under the car, dig out the sealing ring with a screwdriver or spike. Then clean all the oil off the base of the filter housing
Still under the car, dig out the sealing ring with a screwdriver or spike. Then clean all the oil off the base of the filter housing
Lightly grease and fit a new sealing ring. Make sure it is level and properly seated; an oil leak here could prove highly expensive
Lightly grease and fit a new sealing ring. Make sure it is level and properly seated; an oil leak here could prove highly expensive

Clean the filter bowl and other metal components in paraffin and wipe them dry. Fit the new element into the canister (some have to go in right way round). Put the new sealing ring into its groove and reassemble.

Discard the oil filter, but retain· the filter seat. This is a dished ring (centre of picture) and must be replaced right way up
Discard the oil filter, but retain· the filter seat. This is a dished ring (centre of picture) and must be replaced right way up
emove the spring and related components, noting the order in which they come out, and wash them and the filter seat in petrol
emove the spring and related components, noting the order in which they come out, and wash them and the filter seat in petrol
With the canister also cleaned and the spring back in place, replace the filter seat. Check again that it is right way up

Do not use excessive muscle in tightening the securing bolt; wrist-tension is sufficient. But do make sure that the rim of the canister is seated squarely on the sealing ring as an oil leak can easily develop here.

Disposable-type filters usually need about half a litre (a pint) of oil, over and above the engine’s oil capacity. Hence the need to check the oil level twice when refilling the sump.


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