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Oil Common Sense.

Q: What is the difference between a bucket of oil and a 4x4?
A: The bucket won't leak.
Q: How do you know when your 4WD's oil needs topping up?
A: It's stopped leaking.

Most engines in "normal use" die primarily of cold-start wear and internal corrosion. Normal use is: to and from work, shopping a couple of times a week, and longer trips two or three times a month, 8K to 15K miles a year.

Oil drains down in a standing engine. It takes a few seconds for oil-pressure to build-up on a restart; the oil is thick and the moving parts cold, not yet at their working temperature and size. Fuel does not burn well in the cold cylinders. Some condenses on the cylinder walls and gets past the rings into the sump where it dilutes the oil. Water, acid and soot accompany it. Engine oil includes additives to neutralise combustion products, but cheaper oils are more marginal in their capabilities. Changing the oil regularly is the best way to help.

Taxis are well known for running huge mileages before engine rebuilds. A taxi engine might spend its life running almost continually under near optimal conditions. Any fuel and water that does get into the sump is evaporated by the heat.

"Shopping cars" often show a stable oil-level when used around town but suddenly show a drop in oil-level on a long trip. This is caused by the accumulated fuel and water in the sump, that was masking a slight usage of oil, being evaporated off on the first long trip.

Engines used in racing operate under quite abnormal conditions, running at full power for most of their short lives. They need an oil able to stand extreme temperatures and pressures for a couple of hours. They only have a few starts and never get the chance to corrode. An exotic oil advertised on its racing ability is not very relevant to "normal" driving; it won't do any harm to use one, but you would get more benefit from using the car manufacturer's recommended oil and changing it more often.

Get to know your 4x4. It does not matter if it uses a little oil, but a sudden change is a warning. Turbo-charged engines and diesels place special demands on engine oil and the manufacturer's recommendations should be followed religiously. Engines with hydraulic tappets are vulnerable to neglect and to the build-up of sludge; change the oil frequently. The old chestnut about PTFE and other oil additives crops up on the `rec.autos.misc' newsgroup every few months; every car manufacturer would recommend the additives if they were so good but in fact they can do harm. URL:/4WD.html


Oil Changing.

Oil changing is one of the simplest jobs that an owner can do. In many engines, the oil-pump is not within the sump, ie. it is above the oil-level and is not self-priming. There is a check-valve to stop the oil draining out of the system but this could leak when the sump is empty so it pays to be quick; that's brisk, not in a panic. Check with the car's manual.

First get everything ready: new filter, recommended oil, bowl to catch old oil, container to put it in, funnel, spanner, new sump-plug washer, rags. Fill up the new spin-on filter cartridge (if that is what your car uses) with fresh oil. This reduces the time that it will take for the new oil to get pumped around the system. It takes several goes to top the cartridge up. Get the engine warm; this is to help the oil to flow and to stir up any sediment.

Fortunately, there is a lot of room to work under the typical 4WD. Position the bowl to catch the drained oil. Loosen the sump-plug. Undo the plug the last few turns, ow, ouch, is it really that hot? See the oil spurt out sideways with surprising force, missing the bowl, and spraying off chassis rails and steering components. Ow, ouch, yes it really is that hot. Juggle the bowl to catch most of the oil. Drop the plug and washer in the bowl, damn! Removing the oil-filler cap lets the oil drain more smoothly and quickly.

Fish the sump-plug out of the bowl (ouch) as the flow drops to a trickle, and refit it using a new, correct washer. Top up the engine with new oil to somewhere between the `high' and `low' marks, trying not to do any more impromptu rust-proofing.

The old oil-filter can now be removed. Old oil will run out if it is mounted in a silly upside-down position. You might catch most of this with a judiciously placed ice-cream container, possible hacked about for the purpose. The new filter should be spun on without delay, but be very careful indeed not to cross-thread it and not to over-tighten it: read the instructions. If it is mounted upside-down some oil will run out, oh well, try to catch it with a strategically placed floor.

If you have been quick, the system should still be substantially full of oil and the pressure should show normal moments after the engine is started. Some people disconnect the ignition and spin the engine on the starter-motor until the oil-pressure begins to rise before starting up.

Run the engine for a little while and then stop it. Check for oil-leaks and check the oil-level, topping it up to the correct level.

Please dispose of the old oil in a responsible way. Most local councils organize free dump-stations at nominated garages. Old oil is recycled, either as fuel-oil for ships or as a component of "new" lubricating oil.

I am told that you can make a useful gadget to catch the sump-plug and the hot stream of old oil from a 4" pipe-bend by covering one end with mesh. Held up to the sump-plug, it redirect the oil-flow downwards into the bowl until the flow slackens and the mesh catches the plug. I'm going to try it next time!

Oil, petrol and diesel contain unpleasant chemicals. There are unanswered questions over the benzene content of unleaded petrol. Benzene is extremely carcinogenic. Whatever, it pays to minimise your contact with fuel, and with oil which will contain some fuel. Consider using barrier cream on your hands, wearing rubber gloves, and certainly washing hands after the job is done.


Some Common Faults.

Oil is milky brown: contains water, possibly from wading or coolant leakage (head gasket etc.) - change oil asap and rectify any fault.
Engine blows blue smoke under acceleration: possible worn rings.
Engine emits puff of dark smoke after idling: possible worn valve-stem seals.
Oil-level too high: the crankshaft and con' rods will hit the oil in the sump, beat it into a froth and aerate it. Aerated oil is a poor lubricant. It also gives the effect of oil drain-down after standing which can lead to the symptom of a "rattle" on start-up. Drain oil to correct level.


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