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Author Topic: An artical about oil I thought was interisting  (Read 6295 times)
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« on: July 16, 2004, 08:42:08 AM »

Lubrication myths and older cars

Presenter:  Clark A. Kibler; Member, Society of Automotive Engineers (30 years)


“All generalizations are false, including this one. Voltaire


1]  Paraffin base oils make the best engine oils

2] Switching oil brands can cause big engine problems

3] Detergent type oil in an older engine is a really bad thing

4] Straight 40 wt oil is fine for cold weather starts (40F)

5] SAE 5w30 oil is way to thin for engines in Texas summers

6] Oil additives extend the life of my engine and make it run better

7] Synthetic oil is a big rip-off and not good for my old car

8] 600W oil is the very best oil for the steering gear and differential on my old car

9] Most greases are really all the same

10] SAE 90 wt gear oil is more than twice as thick as SAE 40wt engine oil.



(A) Someone will have some emotional viewpoints on each of the above.

(B) Someone will have some experience on each  the above.  

(C) There exist some physical truths about the myths listed.  Each of the above myths are false (as far as generalizations can go)

We won't debate A and B aspects, but present C along with some personal experiences.


Myth 1

Paraffin base oils make the best engine oils.

Paraffin base crude oil stocks are very good indeed for the manufacture of finished lubricants.  Most of the wax needs to be removed from the refined product, but additive solubility is good and oxidative stability is good.  However, today's refinery technology allows the input of many various types of crude oil base stocks, ending up with a finished lube stock that can be identical to a lube stock derived from paraffin base crude stock.  Therefore the advertising claim that one oil is better than another because it is derived from a paraffin base crude stock is meaningless.  The wax (paraffin) removed from crude oil is typically a form of micro-crystalline wax commonly used to make candles, ski wax, and sealing jars of home canned goods.


Myth 2

Switching oil brands can cause big engine problems

Towards the end of WW II the military identified a need to establish compatibility between engine oils used in tactical vehicles.  It was considered undesirable to mix engine oils in a tank engine and have it plug the oil pump intake due to unexpected precipitates, or deposits, from additive incompatibility; and seize the motor.  Standards and tests were adopted to insure that all oils used by the military were compatible with each other.  Not to say that they all performed the same with wear protection, low temp viscosity, etc;  but that they would not create a major problem with respect to circulation.  So, today there are compatibility standards that apply to all API rated engine oils so that mixing oils, or changing brands, does not result in a major problem.  Again, the best performance of an engine oil will be attained by using only one brand at a time because that oil formulation is optimized for the API classification that applies.


Myth 3

Detergent type oil in an older engine is a really bad thing

It isn't Tide® or Cheer® that is poured into the oil when being blended, but one or two of a family of oil soluble salts that help to either disperse gums and varnishes, or to suspend them along with small particulates resulting from combustion by-products.  These are commonly referred to as "ash type"¯ and "ashless type".  Ash types use metallic salts based on calcium or magnesium, ashless are organic derivation and will result in fewer combustion chamber deposits, especially in constant RPM engines such as in airplanes.  In very old engines there were rarely oil filters, and oil technology was not good.  Fuel quality was very poor.  Sludges and varnishes and rust were big problems. Detergent oils were unheard of.  As newer engines evolved, new problems surfaced, especially in the 1949 Oldsmobile overhead valve engine.  This engine represents a turning point in engine oil requirements and technology.  Camshafts were wearing out, sludges were very bad, engine life short.  So a new oil design with detergents, dispersants, and more anti-wear agents was developed.  During this time there were also advances being made with additives called Viscosity Index Improvers (VII) to allow an oil to thin out less with an increase in temperature, and the start of "multi grade" oils.  So new technology allows an oil to flow well at low temperatures and circulate quickly at start-up, and still provide good viscosity for wear protection at higher operating temperatures.


If an older engine that has always been run on a non-detergent oil and is switched to a detergent oil, expect the insides of the engine to slowly get cleaned up.  Wear rates of cams and lifters will be reduced.  Piston ring and bore wear will be less.  However, initially the oil should be changed more frequently, as well as filters if so equipped.  If oil consumption is very high, consider switching to an aircraft type ashless oil of 40 or 50 wt (would be designated aero 80 or aero 100).


So if the old engine is a new rebuild, absolutely start out with a premium multi grade detergent oil, or premium synthetic oil of the correct viscosity.

If the engine is very old and full of deposits, "it all depends".


Myth 4

Straight 40 wt oil is fine for engine starts in freezing temperatures.

Nope.  It is very viscous and close to the pour point of the oil at 32F.  The pour point is the temperature at which the oil becomes solid and will not flow at all.  It would typically be a solid around +10F.  At the very least the circulation of the oil to upper parts of the engine would be very slow and valve train components would run without oil for 3 to 5 minutes.  Way better to use a "multi-grade" or "cross-grade" oil like SAE 10w30 or SAE 15w40 engine oil.  Straight grade oils are not even recommended for heavy duty diesel engines any longer by the major manufacturers like CAT, Cummins, Detroit Diesel and Mack; who primarily recommend an SAE 10w30 for all temperatures except very cold.


Myth 5

SAE 5w30 oil is too thin for engines operating in Texas summer heat.

Before September of 1980 the 5w30 oil of today would have been called an SAE 10w30.  They changed the rules of low temperature viscosity measurement at that time.  So for openers, the 5w30 oil of today is not really as thin as you think it is in comparison to what most of us grew up with.  Add to that the higher quality of base stocks, along with higher viscosity index of the oils in use today;  the film strength is very good at high engine operating temperatures with an SAE 5w30.  There is even a special test to measure that property, which is a part of the API performance category system.  (High Temperature/High Shear test or HTHS)  So if your oil consumption is not excessive, a 5w30 oil is fine for any engine in Texas heat, old or new.  At 210F it is the same viscosity as a straight 30 wt oil.


Myth 6

Oil additives are very good for my engine

Two basic families of additives exist for use over the counter: thick ones, and thin ones.  

Thick ones usually have a big slug of viscosity index improver mixed with a high viscosity oil, and some zinc salts to help with anti-wear.  They are intended to cover up noises from worn engine parts and might be something to consider if trying to sell a noisy motor to someone you will never see again.

Thin ones are intended to free up stuck things:, such as lifters and other parts which are sludged up or have heavy deposits from going too long between oil changes, or using lousy oil.  They smell good due to the aromatic hydrocarbons present.  They reduce the viscosity of the oil to which they are added.  They may also contain some zinc anti-wear additives.  New car owner's manuals caution against the use of oil additives, and can void warranties if they are found to be used and an engine fails.  If you use a good quality engine oil, and then add things to it, the potential exists to upset the careful balance of performance that the oil has from the oil manufacturer.  It might not provide the rust protection of the straight oil, it might form a sludge deposit resulting in "Jello®" in the oil pan, it might wear the engine faster, it will definitely lighten up your wallet.

One exception:  On a brand new engine with a high lift camshaft and stiff valve springs, it is wise to use a one pint can of GM engine oil supplement (or similar) for the first 200 to 300 miles, then drain and fill with fresh oil.  This helps to prevent premature wear on the cam lobes and lifter faces until a proper wear surface is generated.


Myth 7

Synthetic oil is a big rip-off and not good for my old car.

All engines old or new are made up of three mechanical components:  Gears; Bearings; and Cylinders.  In an old or new car, synthetic oil, and specifically Mobil 1® synthetic oil, will pretty much stop wear if used in a mechanically sound engine.  If we were only concerned about lubricating those three components, selecting an oil would be easy.  With an engine we add in the by-products of combusting a hydrocarbon fuel at high temperatures with sulfur present, and water vapor a major component, along with lots of nitrogen. (air we breathe and going into your engine has around 80 percent nitrogen).  Nitration and oxidation become big factors in the life of an oil, along with viscosity retention and wear and rust prevention.  Well blended synthetic oils do all of this way better than mineral oils which are refined from many complex hydrocarbons.  The synthetics used in engine oils are typically a hand built molecule started from ethylene gas, and put together to be one very predictably high performing liquid with a high natural viscosity index.  It has a low vapor pressure resulting in lower oil consumption as compared to conventional oils.  Oil drain intervals are typically extended based on the type of service and helps to defray the added yearly cost, but over the long haul it will totally prevent wear in a new engine be it in an old car or a new one.  Porsche, Mercedes AMG, Dodge Viper, and Corvette all fill from the factory with Mobil 1 synthetic oil because they are assured of lower warranty issues. It is a very good value.  Also makes more horsepower, and gets better gas mileage.


Myth 8

600W® gear oil is the only good oil for the steering gear and differential of my old car.

Many older cars, including Model A Fords, recommend the use of "600W" oil for steering gear and rear end components.  600W was a trademark name by Mobil Oil® (Socony Vacuum back then) for a steam cylinder lubricant that had a high viscosity base oil blended with a fatty acid tallow that was good for lubricity and resisted moisture present in a steam cylinder.  It worked pretty good in worm gears and old spiral bevel gear systems, and was about as good as it got for the 1920s.  In the SAE gear viscosity system, it is about an SAE 140wt.  It is still available in 5 gallon pails from Exxon Mobil jobbers because it is still used to lubricate steam cylinders.  An good alternate choice would be a 140wt gear oil GL 4 or 5.  For a good running rear spiral bevel gear (e.g all pre-48 Ford cars and trucks) a common 90 wt gear oil would be optimum.  The pour point on 600W is +15 F so in very low temperatures the product would channel and not lubricate.


Myth 9

Most all greases are all the same
Grease is basically an oil with a thickener.  The thickener is usually some type of soap complex which acts as a sponge to hold the oil, and is at a ratio of around 80% oil to 20% soap thickener.  Very high temperature grease uses a clay (bentonite) thickener.  There are several variables in grease that influence the choice for a given application:

                1]  oil viscosity

                2]  thickener type and properties

                3]  EP or anti-wear additives

                4]  Dropping point

The application should dictate the selection of the grease.  A high speed bearing wants a light viscosity oil component but a stiff soap component.  EP (extreme pressure additive) is not needed.  A low speed bearing wants a high viscosity oil.  A high temperature application wants a high viscosity oil with good resistance to oxidation and a high dropping point.  A low temperature application wants a low viscosity oil.  A heavily loaded bearing with shock loads wants fairly high viscosity but lots of EP.  It is hard to get one grease to fit all of these different applications, hence many types of grease are marketed by all oil companies.  An premium all purpose chassis grease is usually sufficient for most automotive applications.  These are usually a poly-urea soap base or a lithium complex soap base, and are far more advanced than any grease that was available prior to the 1960s.





Myth 10

SAE 90 wt gear oil is twice as thick as SAE 40wt engine oil

Nope.  They are just about exactly the same viscosity.  Per the chart, SAE gear oil viscosities are on a different scale than engine oil viscosities.  Originally, the gear oil was rated by how many seconds it took for a fixed volume of oil to flow from an orifice device at 210 Fahrenheit.  A 90wt gear oil would have been a 90 Saybolt Seconds Universal (SUS or SSU) oil at 210 degrees Fahrenheit.  The gear oil typically has a lot of EP additives what would not be suited for an internal combustion engine, and the engine oil does not have enough EP for loaded hypoid gears.  Manual transmissions are a n entirely different subject.  A manual transmission with bronze synchronizers will perform fine with a 5w30 or 10w30 engine oil, and use of a 90wt EP oil can lead to the familiar ggrrlitch when engaging the second or high gear quickly. (due to high amounts of sulfur in the EP additive reacting with the copper alloy of the bronze ring).  Most all new car manual transmissions use a very light viscosity oil similar to ATF.  Heavy duty trucks using Eaton or Fuller transmissions recommend a 40 or 50wt engine oil grade but a special synthetic version for 100,000 mile warranties.





Copper is a catalyst for hydrocarbon fuels and oils, and leads to gumming and varnishing of the fluid.  Copper should NEVER be used for fuel lines.  Steel or proper elastomer only.


Water has a viscosity thinner than #1 diesel fuel, and a lower viscosity index.


Oil viscosity increases exponentially with the load applied to it.  Water does not.


Water is much thinner right before it boils than it is at 38 degrees Fahrenheit.


Oil and water are both Newtonian Fluids.  Grease is non-Newtonian.


Water is a poor lubricant but conducts heat very well.


ASTM is the American Society of Testing & Materials: Defines the tests and methods for testing oil

SAE is the Society of Automotive Engineers: Chooses the ASTM performance tests to define oils

API is the American Petroleum Institute: Establishes oil rating standards/system based on the SAE

The three societies working together are called the Tripartite Oil rating system


Taken from the 1910 Ford Model T Instruction Book:


"The Kind of Oil to Use"

"We recommend only light high grade gas engine oil for use in the Model T motor.  A light grade of oil is preferred, as it will naturally reach the bearing surfaces with greater ease, and, consequently, less heat will develop on account of friction.  The oil should, however, have sufficient body so that the pressure between the two bearing surfaces will not force the oil out and allow the metal to come in actual contact.  Heavy and inferior oils have a tendency to carbonize quickly, also gum up the piston rings and valve stems."


Every bit of this is still true today for new automobiles almost 100 years later.
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« Last Edit: June 09, 2013, 10:11:57 AM by Blake Malkamaki » Logged
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« Reply #1 on: June 08, 2013, 01:55:22 PM »

Great article. That's why I am bumping it to the top.
The internet is absolutely awash with arguments and comments about detergent vs. non-detergent, just to mention one topic.

Interesting to read at the bottom that copper should not be use for fuel lines? Comments?

Specialising in Oliver & Cletrac Crawlers & Parts for HG's, OC-3's & OC-4's from the 30's to the 60's. OC-6 and others from time
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« Reply #2 on: June 09, 2013, 10:15:45 AM »

Thanks for bringing this back up Chris. It almost deserves being made into a sticky topic or put in the technical section of the web site.


My gramps Howard van Driest was Experimental Engineer at Cletrac and Oliver Corporation. After the plant closed, he and my uncle started an excavating business, initially using Cletrac and Oliver Crawler tractors. Please help Support This Site and give your business exposure by buying a business card sized ad.
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« Reply #3 on: June 10, 2013, 01:49:32 PM »

Yeah, I was surprised to read about the copper fuel lines. I'd like to see some supporting evidence. I know a lot of fuel lines and even brake lines on older vehicles and equipment were/are copper.

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« Reply #4 on: June 10, 2013, 04:03:31 PM »

I doubt there is enough contact time between the fuel and the copper to create much of a reaction. And I bet if you look at the inside of the tubing it is coated with varnish from the gasoline, therefore not actually contacting the fuel at all.

My gramps Howard van Driest was Experimental Engineer at Cletrac and Oliver Corporation. After the plant closed, he and my uncle started an excavating business, initially using Cletrac and Oliver Crawler tractors. Please help Support This Site and give your business exposure by buying a business card sized ad.
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« Reply #5 on: June 21, 2013, 11:45:16 AM »

Copper should not be used for Brake Lines. The wall strength is not as high as steel tubing and can burst at any time pressure is applied to the brakes.
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« Reply #6 on: June 21, 2013, 02:00:51 PM »

Actually I believe the brake lines where an alloy of 90% copper and 10% nickle. It wasn't that unusual at all to find copper brake lines in older vehicles. I believe at one time it was preferred over steel because the mild steel lines would rust and burst.

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