Engine Oil

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Original submission by T, July 24th 2006;

Back to the Engine Section

Photo by Mynew69ht. The Oil Filler Cap on an HT 186 Kingswood. White emulsion is water vapour which can be caused by an excessive number of short runs without the correct driving intervals in between. Note the heavy buildup of carbon caused by the lag in the engine oil temperature. The engine has not been getting hot enough for long enough.

Engine Oil:

Engine Oil Grades:

Photo by Mynew69ht. Engine Oil on the top of the Rocker Cover around the Oil Filler hole shows that the piston rings are gummed up and allowing excessive blowby past the rings. Another legacy of short runs, warming up or improper running in general.
White Sludge formed under the Oil Filler Cap of a Grey 138 cu in Holden Six Cylinder Engine. Lots of Short Runs that don't allow the Oil to fully heat up are a major cause of this problem. Click to Enlargen. Photo by Scott4571.
Gunk buildup in an Holden red Six as a result of improper use and/or maintenance. Photo by HR Ambo. Click to Enlargen.
Car manufacturers make recommendations about the Oil that should be used in each particular model of car.
They also add recommendations that are consistent with the use that model will see. A car that's used at sea-level at normal to high temperatures may need a heavier Oil than the same model run at higher altitudes and lower Temperatures.
202 with around 750,000kms. No warming up or short runs. Note the inner cleanliness. Photo by T. Click to Enlargen.
Photo by Qute. The Image shows the areas in the top of the Engine and on the side that trap cold Oil
Photo by Qute. The Oil Filter is visible, white and in the lower centre of the Image.

It's wise to observe any manufacturer's Oil recommendation and only vary from that after an investigation that proves the alternative Oil will cover all the requirements for that Engine used in a particular way.
The number 2 Bigend Bearing  failed which caused a Conrod to punch through the side of the block right where the 3.3 embossment used to be. This can be a typical outcome from Oil and Oil Filter neglect. Click to Enlargen. Photo by Dusty Dirt Roads.

Racing Oils:

There's little doubt that these Oils show advantages in competition. One of the reasons they do is because they contain fewer anti-contamination countering agents. Racing Oils are intended to be used in a one day competition. Using them over the long term can have long term side effects.

Non-Racing Oils:

These Oils contain agents that help to make the Oil last the months until the next Oil Change. The agents minimise the side effects of Oil contamination on the Engine.
Non-adjustable Valve Gear in a 173. Although there is discolouration of the No 5 Inlet Valve Pushrod, the possible cause being a failed Rocker to Pushrod Bearing allowing Oil to leak back down the Pushrod, the state of cleanliness is good because this high time engine has had its lubrication properly managed.  Image by Red Seat. Click to Enlargen

The Effect of Temperature:

While a Temperature too low can impact the life of an Engine, a low Temperature can extend the life of Engine Oil. Engine Oil that runs excessively hot will blacken rapidly making it due for change sooner.

Oil Changes:

Oil should be changed when the manufacturer recommends it. When the Engine Oil appears black on the Dipstick, both the Oil and the Oil Filter are overdue for changing.  If the Oil appears to be a Coffee colour, then this indicates that water and oil have mixed in the sump.  This usually means a cracked Head or Head Gasket.

False Readings:

Sump Dents:

Engines are often sat on their sumps in Wrecking Yards and Rebuild Shops. This can cause the bottom of the Sump to collapse. As a result the amount of Oil the Engine holds will be reduced when measured by the Dipstick. Engines should be bolted into a professional support frame during storage as shown in the lowest image.
Showing how close the Crankshaft is to the Oil. The Oil Pick-up Tube and Strainer can be seen on the lower right hand side. Photo by Jacks

Dipstick Errors:

Also, the Dipstick Tube or the Dipstick itself can become displaced and delve too far into the sump,
or not far enough. The result can be a False Reading. A False Reading can lead to Over or Under Filling.
Does the Engine have the correct Dipstick? There have been occasions on Red Sixes and Blue/Black Engines in WB's where the Dipstick has been positioned badly in the block. As a result the Dipstick can collide with the number 5 Bigend. This can be associated with a clicking sound
and or the end of the Dipstick being broken off.
179 Engine. Photo by Jacks.

High Flow-Rate Oil Pumps:

There have been instances where high flow rate Oil Pumps have been fitted to Engines without
the Oil return holes being increased in size to match. As a consequence Oil tends to become trapped in the Valve Gear and a low Dipstick reading appear. Under these conditions it's possible that the Oil Pump can become starved for Oil and
make the Oil Pressure Gauge and or Light Flicker or show low Oil Pressure.

Parking the Vehicle on a Slope:

Parking the Car on a slope will upset the level of Oil in the Sump and cause a false reading.

Getting the Best From the Oil You Use:

Short Runs:

The short answer is, avoid them. Cars that do a lot of short runs suffer from Oil Dilution. Every Cold Start puts Water and Fuel into the Sump. The Engine is dependent on hot runs to make these additions evaporate out. If insufficient hot running occurs, the Engine Oil Level can appear to remain steady or even rise. During the first long hot run, the water and fuel will evaporate off. Subsequent checking of the Oil Level will show that the level has dropped drastically. All Engines burn Oil. Excessive short runs can mask this fact. If you are forced to make short runs, offset them by making longer runs that heat the engine to normal temperature for an hour or more. This is part of the same program that will give you the longest Engine life. Engine Oil can take up to 20 mins to reach a temperature high enough to evaporate out Water. If the Engine Oil does not become hot enough deposits of emulsified Oil and Water will develop within the Engine as the photo with the Oil Filler Cap removed shows. 
Holden 161 engine as originally used in HD Holdens. Click to Enlargen. Photo by Qute.
Poor Oil management has resulted in this thick accumulation of goo in the bottom of the Sump in a 179. Click to Enlargen. Photo by HRAmbo.

The Warmup Myth:

Warming an Engine up at idle and with no load is a great way to contaminate the Oil and gum up the Piston Rin Grooves. One problem is that the Compression Rings are insufficiently charged to gas pressurise properly. This makes it the ideal time
for Oil/Fuel/Water/Carbon deposits to collect in the Piston Ring Grooves and destroy the Piston and Piston Ring Groove's ability to manage the combustion charge properly. Much has been published about this under PCV. Start the Car and drive off moderately, avoiding full throttle until normal temperture shows on the Temperature Gauge.

The Cold Starts Wears Out Engines Myth:

Look around the wrecking yards at any pulled apart Engine and you'll see Oil all over every internal part. The Crankshaft Oil ways and Engine Block Galleries will be full of it. There's no reason to assume that a high degree of wear will occur on an Engine during a cold start. The amount of Engine wear sustained from a Cold Start is tiny. The apparent cause of Engine Wear from a Cold Start is caused by Warming Up as mentioned above. Gummed up Piston Rings is frequently mis-diagnosed as worn out Piston Rings, Bores and Pistons when in fact short runs and warming up has filled the Piston Ring Grooves with carbon and defeated gas pressurisation of the Compression Rings.

Don't Overrun the Oil Change Interval:

By the time the Oil shows as black on the Dipstick, an Oil Change is overdue. By this stage the Oil will be full of contaminants and to some extent have lost its lubricational abilities. While this Oil can be recovered by a refinery, there's no practical way to recover it at home. Dirty Oil will layer the Engine with Carbon and discolour the surfaces. The small amounts of carbon in the Oil will accumulate in corners of the Galleries and in the bottom of the Valve Lifters. Changing the Oil when it's required and keeping the Oil clean is one strong factor in achieving maximum Engine life.

Checking the Engine Oil Level:

Car manufacturers post recommendations about the proper way to read the Engine Oil Level for good reason.

When to Check the Engine Oil Level:

After a Rebuild:

This is the time to pay the greatest attention to filling the Engine with Oil. You should establish the amount of Oil the Engine is expected to hold and take accurate note of how much is poured in.
179 Engine. The Image shows a professional stand for storing Engines. This prevents the Sump from being dented. Photo by Jacks.

Fill the Oil Filter before fitting it, then add the remaining Oil into the Engine slowly, periodically checking the Dipstick level to make sure the level matches your expectation. If the Dipstick reads "full" before the expected amount has been poured in, then you should investigate.
Likewise if the Dipstick Level is still low after the full amount has been added you should investigate further to reveal the reason. If the Diptick Tube is found to be too far into the Sump it can be repositioned by inserting a Phillips Screwdriver into it ( so that it won't become crushed) and twisting it out with pliers. If the Diptick Tube is found to be too far out of the Sump it can be repositioned by inserting a Phillips Screwdriver into it ( so that it won't become bent) and gently tapping it deeper into the Sump until it reads correctly. Check the False Readings Section if a disparity appears.

During Normal Use:

After a Hot Run:

The hot Engine Oil Level should only be checked with the vehicle parked on level ground at least 10 minutes after shutdown. It's important to observe a wait period because the oil can take some time to run back into the sump.
If the Dipstick is read before the Oil has had time to run back into the Sump, the reading will appear to be low. Topping up the level prematurely will result in the Engine Oil Level being too high.

Checking the Level with the Engine Cold:

A particularly good time to check the Engine Oil Level is the day after a long run that occurred the previous day. That way the Oil has had hours to drain back into the Sump. Make sure the vehicle was parked on a flat level surface and the Engine left shutdown overnight. A particularly bad time is when the driver dips the Oil on a cold Engine after a short drive to the local petrol station. Under this circumstance, a good deal of Oil is trapped in the Valve Gear and is not able to run back into the sump. Dipping the Oil and topping up the level will result in the Sump being overfilled when the trapped Oil heats up, thins out and finally runs back into the sump.

During Very Cold Conditions:

The Engine Oil may not have reached sufficient Temperature even after a 30 minute drive. As a result the Oil's Viscosity will still be thick and not allow the Oil to drain back from the Rockers properly. This will give a false reading saying the Oil Level is low. Check the Oil Temperature by touching the Dipstick.


This can be dangerous to the life of the Engine as well as Vehicle occupants if the Engine should seize. Underfilling can cause the Engine to run at higher than normal temperatures. Higher temperatures will blacken the Oil quicker.


Overfilling of the sump can cause the Crankshaft Balance Weights and Conrods to dip into the Oil.
When this happens the amount of Oil flung around can exceed the Sump Gaskets' ability to retain the Oil. It can also cause Oil to drip from the Front and Rear Seals and in some cases the Fuel Pump. It can also froth the Oil leading to compound lubrication problems including noisey Valve Lifters. Oil burning can result.

Engine Oil Burning:

Several factors can cause or contribute to an Engine burning Oil.

Engine Wear:

The common answer for this is worn Pistons, Rings and Bores. Worn Valve Guides and worn Main and Big End Bearings is another. Often the causes of Oil Burning can be simpler and easier to fix, though the reasons are less obvious.

Improper Use of the Car:

The Engine's Oil Burning may be a deception caused by improper use. In other words the normal burn rate of Oil has become masked by the addition of Fuel and Water during Cold Starts but made worse by Short Runs. When the Fuel and Water evaporate the Oil Level returns to what it would have been had the Car seen proper use. See Short Runs for further details.

Rocker Cover Baffles:

As posted under PCV , the absence of Rocker Cover Baffles inside the Rocker Cover is a hidden cause of Oil Burning.

Oil Filter:

It's no secret that the Oil Filter is there to collect unwanted contaminants. An Oil Filter that has run its life will no longer be able to perform its function correctly. The Oil Filter should be replaced with every Oil change or when the manufacturer recommends.


The Oil Pressure Light or Gauge Fluctuates:

Low Oil Level.
Faulty Sender Unit.
Faulty Gauge or Light Bulb or Light Bulb Holder.
Loose wiring between the Sender and Bulb or Gauge.
Blockage in the Pickup Tube.
Breakage in the Oil Pickup Tube allowing air in.
Faulty Oil Pump Drive.
Loose or missing Camshaft Gallery Plug.


As bizarre as it sounds, people really do confuse Dipsticks on Automatic Cars then pour Engine Oil into the Gearbox or Automatic Transmission Fluid into the Engine or do both. Avoid pouring any used Oil back into the Engine. This is easy to do and defeats the purpose of changing the Oil. Place the old Oil far enough away from your work area so this can't happen. Avoid throwing your new Oil out as a result of the same confusion. Make sure the Sump Plug is in place and secured before pouring in any Oil.
The Oil Filter can need reseating after the first hot run because the Gasket can shrink.
Dipstick showing Coffee coloured oil, which indicates that water has found its way into the sump. Causes of this include a cracked Head or Head gasket. Photo by Snyperdaemon.
Sludge in the Valley of a VN V6 due to Oil neglect . Photo by Fx48_eh64.
Sludge on the underside of the Inlet Manifold of a VN V6 due to Oil neglect. Photo by Fx48_eh64.
Z30 Oil Filter on a 3.3 VK Engine. Photo by Faust Fuhrer. Click to Enlargen.
Z30 Oil Filter on a 202 Engine. Photo by WBLJE.  Click to Enlargen.
Incorrect running coupled with incorrect Oil Change Intervals result in moulded Sludge inside the Engine. Photo by Juzzy. Click to Enlargen.
Where the Oil is held if you Dip the Level before it has time to run back into the Sump. Photo by Red Seat. Click to Enlargen.


Oil Filters

Dusty's Catastrophic Failure Collection
Engine Lubrication Chart (The Good Oil from Jacks).

L6 Oil Pumps. (Maybe the Pumps was too Much?).
Priming L6 Oil Pumps. (Manning the Pumps).
Engine Oil Leaks (Preserving the life blood).
Oil Pressure (The Blow Off).



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