Willys Hotchkiss Jeeps
Willys Hotchkiss JeepsWillys Hotchkiss Jeeps

Oil change top tips for jeeps.

The oil change process is pretty straight forward.

After running the engine for a short while, and the engine is up to operating temperature, stop the engine and remove the sump bung from the bottom of the sump.

As there should only be about 4.5 litres of oil in the engine, sometimes I cut the side out of a used oil container (that the oil comes in) lay this down on the floor and drain the used oil into this.  This saves buying or making a mess with a purpose built oil pan!

Make sure you wear gloves as the oil is extremely hot and has a tendency to run down your arm if you don't get the plug out quickly enough.

Don't worry if you loose the plug onto the floor or the oil container - fish it out later when the engine is fully drained..

Once the oil has reduced its flow to a dribble, I sometimes flush the engine with about a quarter of a litre of the new engine oil, until the oil runs out clear (ish)  Don't worry as you have probably purchased 5 litres (hopefully you have as instructed in the previous blog!), and you only really need 4.5 to refill the engine - so you can afford to loose a quarter of a litre now.

Whilst you have the sump plug out, I usually place a small finger into the drain hole and feel to see what depth I have of sludge in the sump. This isn't a scientific measurement, but if I feel about half a cm or more - I would consider dropping the whole sump (only about 20 bolts) cleaning out (petrol is good to dissolve the gunk!) wiping dry with a cloth (don't use paper as it can leave behind 'sharp' fibres that isn't good for the engine!) and replacing with a fresh new gasket (cheap from jeepparts)

With the sump empty, check the quality of the copper sealing ring - as even a small nick can result in you getting an oil leak all over the sump - leaving you scratching your head to what's leaking now!

Next we take the top off the oil bath (the housing at the front top of the engine!) where the oil filter goes.

Put this top to one side carefully (as there should be a spring under the lid!) and pull out the old oil filter.  I pull them out slowly and  transfer directly to an old plastic bag, so save it spilling old oil all over the rad and front of your jeep!


You now want to get the oil left behind out the oil bath. The reason is to get as much of the old oil out the engine as possible!

For this you will need a clear plastic tube, or at least a cheap fuel/ liquid transfer device - see picture to right.


There is a bung in the bottom of the oil bath, but undoing this on a quarter litre of oil (now you know where the rest of the oil is going!) is very messy.

Syphon off the old oil and clean out the oil bath unit with a lint free cloth (again not paper!) before refilling this bath with new clean oil (to the same level as before)

Drop in the new filter (make sure its the metal canister type - about 12 from Jeepparts) by oiling the rubber holes in the middle of the filter that slip over the central spindle.

Push the filter down and you will see the golden oil level rise and (hopefully) stop just short of the top of the oil bath.

I may propose being controversial here - but I don't replace the rubber lid gasket as supplied with the filter.  There's nothing wrong with it, its just disturbing the original rubber seal (if it's still serviceable) can be fraught with problems.. I say  'if it aint broke, don't fix it' here.

With the top of the oil bath screwed down with a spanner  (don't over tighten) pour in the 4.25 litres of new engine oil down the filler tube at the left side of the engine.  Keep checking the dipstick a few minutes after adding the oil to get an accurate reading of level.

Once you have added enough to fill the dipstick to about 3/4 of the markings - its time to start the engine.


When starting don't rev the engine too much, you want the oil pressure to rise slowly and up to mid point on the dial.  If it is higher that's not an issue, but low oil pressure may mean worn oil pump or a major leak. Don't rev the engine hard as this can create wear, also don't idle your engine for too long as it can over heat and also create wear.. jeeps need to be driven!


As the engine is idling keep an eye on the seal at the top of the oil bath for any leaks.  I can assure you, if this seal was mis-aligned or broken you would notice, the pressure of the oil pump will eject pints of oil in seconds across the fan and engine bay (those observant people may think; 'hmm think he's experienced that before!?')

Stop the engine and check the levels again, when the oil is settled.  If it is still at 3/4 good - add the rest of the fresh oil to bring it closer to the top.

You should find you have about a quarter (or so) of a litre left over.  This is just enough to put in a small oil can you carry with the jeep - to oil things like linkages, knob cabling, and maybe a splash on the handbrake ratchet (to help it come off easier!)

If you have cleaned out the sump - you should get a good few weeks with still a lovely golden oil - maybe longer if your engine isn't too worn. If you haven't and just fitted the filter without draining the oil bath - it may start going black quite quickly..

Hopefully this has helped - and wasn't too patronising for Jeep owners - it's aimed at the new owner who wants to roll up their sleeves and get stuck in!

If you have any specific mechanical issue and you want me to write a brief blog on it - feel free to mail your suggestions through this site.

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