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Engine oil mythology debunked, and ZDP content

Rattlehead

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I received some really good information on engine oils from a respected professional in the field of engine oil development. He has also written, with another author, a SAE paper titled "How Much ZDP is Enough?". It is SAE document #2004-01-2986 if you care to locate it and read in greater detail. I have his permission to share a couple of his personal articles on oil myths.


Here is one:

Engine Oil Mythology

Myths are ill-founded beliefs held uncritically by interested groups. Over the years there has been an overabundance of engine oil myths. One was that the only good oils were oils made from “Pure Pennsylvania Crude Oil.” This one got started before the Second World War when engine oil was crude oil with very minimal refining, and crude oil from Pennsylvania made better engine oil than Texas or California crude. With modern refining, almost any crude can be made into good engine oil.

The next myth was that “modern” detergent engine oils were bad for older engines. This one got started after the Second World War, when the government no longer needed all the detergent oil for the war effort, and it hit the market as Heavy-Duty oil. These new detergent oils gave the pre-war cars, which had been driven way past their normal life and were full of sludge and deposits, a massive enema. In some cases bad things happened such as increased oil consumption – the piston rings were completely worn out and the massive piston deposits were the only thing standing between merely high and horrendous oil consumption. If detergent oils had been available to the public during the war, this myth never would have started.

Amazingly, there are still a few people today, 60 years later, who believe that they need to use non-detergent oil in their older cars. Apparently it takes about 75 years for an oil myth to die.

Then there is the myth that new engines will not break-in on synthetic oils. Apparently there was an aircraft engine manufacturer who once put out a bulletin to this effect. Clearly the thousands and thousands of cars filled with Mobil 1 as factory-fill, which have broken-in quite well, should have put this one to rest. However, this myth is only 40 years old, so it has another 35 years to live.

All of these myths have a common theme; newer oils are bad. And this brings us to the latest myth – new “Starburst”/ API SM engine oils are bad for older cars because the amount of anti-wear additive in them has been reduced. This one has gotten big play in the antique and collector car press lately. The anti-wear additive being discussed is zinc dithiophosphate (ZDP).

Before debunking this myth we need to look at the history of ZDP usage in engine oil.

ZDP has been used for over 60 years as an additive in engine oils to provide wear protection and oxidation stability. Unfortunately, ZDP contains phosphorus, and phosphorus is a poison for automotive catalysts. For this reason ZDP levels have been reduced by about 35% over the last 10-15 years down to a maximum of 0.08% for “Starburst”/API SM oils.

Zinc dithiophosphate was first added to engine oil to control copper/lead bearing corrosion. Starting in 1942, a Chevrolet Stovebolt engine with aftermarket copper/lead insert-bearing connecting rods was used for the standard engine oil qualification test. The insert-bearings were weighed before and after test to evaluate weight loss due to corrosion. The phosphorus levels of oils that passed the test were in the 0.03% range.

In the mid-1950’s, Oldsmobile got into a horsepower war between its Rocket engine and the Chrysler Hemi. Both companies went to high-lift camshafts and both got into camshaft scuffing and wear problems very fast. There were three solutions: 1) better camshaft and lifter metallurgy, 2) phosphating the camshaft, and 3) increasing the phosphorus level from ZDP up to the 0.08% range. In addition, the industry developed a battery of oil tests (“Sequences”), two of which were valve-train scuffing/wear tests.

Knowing that this higher level of ZDP was good for flat-tappet valve-train scuffing and wear, some oil companies, thinking that they were offering the customer additional protection dumped even more into the oil. It was soon learned, however, that, while going above about 0.14% phosphorus might decrease break-in scuffing, longer-term wear increased. Further, at about 0.20% phosphorus, the ZDP started attacking the grain boundaries in the iron, resulting in camshaft spalling.

In the 1970’s, the ZDP level was pushed up to the 0.10% phosphorus range because it was a cheap and effective antioxidant. The increased antioxidancy was needed to protect the oil in Cadillacs pulling Airstream trailers from thickening to a point where the engine could no longer pump it. Recently, the need for this higher level of ZDP to protect the oil from thickening has been greatly reduced with the introduction of modern ashless antioxidants that contain no phosphorus.

Enough history. Getting back to the myth that “Starburst/API SM oils are no good for older cars, the argument put forth by the myth believers is that while these oils work perfectly well in modern, gasoline engines equipped with roller camshafts, they will cause catastrophic wear in older engines equipped with flat-tappet camshafts.

The “Starburst”/API SM oil standards were developed by a group of OEM, oil additive company, and oil company experts. When developing any new engine oil standard, the issue of “backward compatibility” is always of great importance. Indeed, the group of experts spent a lot of time researching this issue. In addition, multiple oil and additive companies ran “no harm” tests on older cars with the new oils; no problems were uncovered.

Beyond the “no-harm” testing, the new “Starburst”/API SM specification contains two valve-train wear tests. One is the Sequence IVA, which tests for camshaft scuffing and wear using a 2.4L Nissan single overhead camshaft engine with slider finger followers. The wear limits for this test were tightened from those of the previous oil specification, even though the old spec had a higher, 0.10%, phosphorous limit. The second test is the Sequence IIIG, which evaluates cam and lifter wear. For this test, a current-production, GM Powertrain 3.8L engine with the valve train replaced with a flat-tappet system, similar to those used in the 1980’s, is used. The only reason for using this older valve-train design is to ensure that older engines are protected. All “Starburst”/API SM oil formulations must pass these two tests.

In addition to the protection offered by these two valve-train wear tests and the “no-harm” testing, a review of the knowledge gained over the years in developing previous categories also indicates that no problem should be expected. For example, the new “Starburst”/API SM oils contain about the same percentage of ZDP as the oils that solved the camshaft scuffing and wear issues back in the 1950’s. They do contain less ZDP than the oils that solved the oil thickening issues in the 1960’s, but that is because they now contain high levels of ashless antioxidants, which were not commercially available in the 1960’s.

The oil’s ZDP level is only one factor in determining the life of an older camshaft or a new aftermarket camshaft. Most of the anecdotal reports of camshaft failures attributed to the newer oils appear to be with aftermarket camshafts. Breaking in extremely aggressive aftermarket camshafts has always been a problem. The legendary Smokey Yunick wrote that his solution to the problem was to buy multiple camshafts and simply try them in a slave engine until he found one that survived break-in without scuffing.

Despite the pains taken in developing special flat-tappet camshaft wear tests that these new oils must pass and the fact that the ZDP level of these new oils is comparable to the level found necessary to protect flat-tappet camshafts in the past, there will still be those who want to believe the myth that “new oils will wear out older engines.” Like other myths before it, history teaches us that it will take about 75 years for this one to die also.


------------------------------------------------------------

The following is from a presentation he gave to a classic car club.

Are Newer Engine Oils Really Bad for Older Cars?


Miracle Drugs/Additives
* Engine oil additives are like drugs:
- More is not necessarily better
- Take just enough to control the problem
- They have side effects, sometimes fatal
- They often interfere with each other
* Formulating engine oils is a balancing act
- Standardized engine testing is used to get the correct balance

Sequence Tests
* Standardized engine tests for determining oil quality have been used for 50 years
* Currently they are:
- Sequence IIIG; viscosity increase, deposits, and wear
- Sequence IVA; scuffing
- Sequence VG; sludge
- Sequence VIB; fuel economy
- Sequence VII; copper/lead bearing corrosion

Sequence IIIG
* The Sequence IIIG test is based on the current 3.8L GM engine
* The engine is retrofitted with a flat tappet valve-train based on the 1987 3.8L Buick
* This ensures that older engines using wear sensitive flat tappet/push rod valve-trains are protected by ILSAC GF-4/API SM oils

Sequence IVA
* This test is based on an out-of-production 2.4L Nissan engine equipped with a single overhead camshaft and finger followers
* This valve-train is similar to that used on the old Ford 2.3L Pinto engine
* This type of valve-train can be more wear prone than the Sequence IIIG valve-train

ILSAC “Starburst”/API SM
* The current oil standard recommended by US and Japanese auto companies incorporates two camshaft scuff/wear tests that are based on non-roller valve-trains to ensure “backward compatibility” of newer oils
* The ILSAC/OIL Committee, which developed this standard, did not “ignore wear issues in older engines and only worry about catalyst life”

Are newer Engine Oils Really Bad for Older Cars?
There is no reason to believe that newer oils will not protect older cars on the road from premature cam and lifter wear. Lets examine why

Why should newer oils protect older engines?
* The ZDP levels in newer oils are comparable to those needed to solve scuff problems encountered in the 1950’s with some older engines
* The newer oils must pass two rigorous camshaft scuff/wear tests (IIIG and IVA)
* Somewhat higher ZDP levels were used in oils in the 1970’s because the ZDP was also being used as an antioxidant
* Ashless antioxidants have reduced the need in today’s oils for ZDP to be used as an antioxidant

Next Question
* Are newer engine oils bad for breaking-in engines rebuilt with flat tappet camshafts?
- The Sequence IIIG and IVA tests start with new cams and lifters with no camshaft pre-lube
* So again the answer is the same: newer oils should protect at least as well as older oils

The Real Question?
* Are newer engine oils bad for breaking-in rebuilt engines equipped with high performance camshafts?

Camshaft Break-in Scuffing
* High performance flat tappet camshaft break-in has always been problematical
* Smokey Yunick said the best way is to order several identical cams, pick the best looking ones, put them in a slave engine, run a break-in, and if one didn’t scuff-use it!

“The devil is in the details”*There are at least 20 different design and production parameters that must be closely controlled to ensure proper camshaft break-in
* Engine oil is just one of them
* Oil tends to get more than its share of attention because the average engine rebuilder can’t do much about things like lifter bore positioning or angularity

“Nothing but the oil changed”
* When something goes wrong, I am always told the oil was the only thing that changed
* Usually many things have changed

You may not like to hear it but…..
There may be no oil in the world that will protect some of these high performance camshafts with excessive lift rates that cause the contact patch to run off the edge of the lifter

What is ZDP?
* Zinc-dialkyl-dithiophosphate
* Abbreviated as ZDP or ZDDP, which ever you prefer
* Forms a polyphosphate tribo film separating the cam lobe from the lifter
* Prevents adhesion of the lobe to the lifter, and break-in scuffing
* Also protects the surfaces from abrasive and corrosive wear

ZDP: the Miracle Drug
* The truly amazing thing is that the ZDP forms this polyphosphate tribo film where it is needed
* A thin film, measured in nanometers, is formed on surfaces as the result of contact pressure and sliding speed
* You only need enough active ZDP to form the film initially and replenish it as it wears away

How Much ZDP is Enough?
* It does not take much ZDP to form these thin films on the wear surfaces
* The ZDP does not “waste itself” forming films on all the surfaces of the crankcase
* ILSAC GF-4/API SM oils contain much more ashless antioxidants, which allow the ZDP to “save itself” for acting as an anti-wear agent instead of an antioxidant

Summary
* The preponderance of dynamometer and vehicle testing indicates that the current level of ZDP in modern passenger car motor oils is more than enough to protect older engines
* If you want to install a high-performance camshaft, invest in a roller-follower cam and lifters
 

Bill W

Well-known member
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Brooks,Ga
Off the top I would like to say that I feel that detergent oil can be bad for older engines that have only bypass filtration ( ie 230 Dodge flatheads ). Non-detergent oils do not hold contaminates in suspension like detergent oils do, ND oil let contaminates fallout to the bottom of the oil pan where the floating oil pickup tube won't pick it up ( in theory ) this way less contaminents get pumped thru the bearings since none of that oil gets filtered before hand like todays fullflow filtering does. Now if you have a fresh ( clean) rebuilt engine then I would have no problems running detergent oil in it but I would change it more often...just my 2cents
 

Rattlehead

Member
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Location
S.E. Michigan
Good theory on the detergent oils with a bypass filter system. Not sure what to think.

The other post on this topic questioned if there was a complete elimination of ZDP for diesel CJ-4 oil, but that doesn't seem to be the case according to this article;

http://www.dieselnet.com/tech/fuel_lube.html

They lowered the max level from 0.14 to 0.12% weight. They could contain less, but that is the max allowed. The oils are still required to meet minimum test specifications. One benefit is that the oil's soot control requirements are improving, required because of the use of EGR on modern diesels. Not that our multifuels produce any soot, or anything.

I would tend to think that even if some compromises were made in newer lubes in some aspects, there are so many other overall improvements when compared to lubes from 50 years ago that you are still probably better off. Of course, I am one of those lunatics that runs GL-5 in my axles instead of GL-1. :twisted:

Now, where can I get my hands on some of that pure Pennsylvania crude for my crankcase!
 

scrapman

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Mmpphh fire bad!:| Excellent reading. Especially interested in the zinc aspect. I'm old guy with grey whiskers so I grew up in a time when some of these beliefs were repeated as the absolute end all truth. Still think Fire Bad!
 
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darknessvanquished

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SW Burbs of Chicago
ZDDP is a very good extreme pressure additive. It is being phased out of API oils because the govt and car manufacturers asked the oil companies to get rid of it for emissions warranty issues with catalytic converters.

This removal/reduction in ZDDP is bad if you run a flat tappet cam because the ZDDP acts as a cushion between the high friction area of the cam lobes and the lifter faces. One way around this is to run diesel oil, non-API "boutique"oil or add a bottle of ZDDP additive to your API oil when you change it. Using/having ZDDP is very, very important if you run a flat tappet cam.
 

Tanner

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Those of us that participate in the air-cooled VW & Porsche engine community & build engines have had flat tappet cam wear issues typically attributed to a lessening of ZDDP in the oils... it isn't anecdotal - I just looked at a Type 4 VW/Porsche motor Wednesday that had no more than 10 hours on it & the new cam & lifters were majorly damaged. Multiple cam/lifter failure stories from performance engine builders have surfaced on the VW forums, and these are from guys that build some of the top motors in the country - I doubt that they would lie about the oils used.

Most of us were/are using Rotella, but the ZDDP content in it was recently reduced. (from 1400ppm to 1200ppm?)

Let me see...
Engines built & using oil with greater amounts of ZDDP > very few to no cam/lifter issues.
Engines built & using oil with less ZDDP > more cam/lifter failures.

Coincidence?

Tanner
 
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darknessvanquished

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Those of us that participate in the air-cooled VW & Porsche engine community & build engines have had flat tappet cam wear issues typically attributed to a lessening of ZDP in the oils... it isn't anecdotal - I just looked at a Type 4 VW/Porsche motor Wednesday that had no more than 10 hours on it & the new cam & lifters were majorly damaged. Multiple cam/lifter failure stories from performance engine builders have surfaced on the VW forums, and these are from guys that build some of the top motors in the country - I doubt that they would lie about the oils used.

Most of us were/are using Rotella, but the ZDP content in it was recently reduced.

Let me see...
Engines built & using oil with greater amounts of ZDP > very few to no cam/lifter issues.
Engines built & using oil with less ZDP > more cam/lifter failures.

Coincidence?

Tanner
Decreased levels of ZDDP are 100% related to flat tappet camshaft wear and failures. ALL of the people in the engine industry know this. EVERY major camshaft manufacturer has issued bulletins on this with the warning to use ZDDP fortified oil or a ZDDP supplement or else you will ruin the cam and lifters. Point blank-It's either run a oil with ZDDP to keep your cam alive or upgrade to a roller cam setup that doesn't "require" the higher level of ZDDP. Even then, I'm a tad skeptical because there's a whole bunch of friction between the lifter's rollers and cam lobes when you are running valve springs with a lot of tension, as is typical in a roller setup, especially with a solid roller cam-they run very stiff springs. Play it safe and run a ZDDP fortified oil for maximum protection regardless if it's a flat or roller cam. Oil is cheap, tearing apart a engine and replacing parts isn't.

Yes, diesel oil has had its ZDDP levels reduced in the past couple of years, but ZDDP is still in there at levels 3-4 times what is in API certified "gasoline" motor oil. Diesel oil for the time being is a excellent way to get ZDDP if you don't want to pay a premium price for boutique oils like Brad Penn, Royal Purple, etc. I run Shell Rotella 5W40 diesel oil in all of my flat tappet cam engines, a 1997 Jeep 4.0 6cyl being the latest model engine to use it.
 

Tanner

Active member
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Location
Raleigh, NC
The API specification change to CJ-4 for 2007 has resulted in moderate zinc reduction from about 1,400 ppm to 1,200 ppm. And even at these slightly decreased levels, ROTELLA T 15W-40 conventional and 5W-40 synthetic still contain three to five times the amount of the desirable anti-wear additives as some current gasoline-engine oils.

Found in a post on jeepforum.com...

'Tanner'
 

nap159

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welch, mn
a lot like the newer trucks that specify 85-140 rear axle oil. I have had bad luck with that. 80-90 has worked fine for many years. now i see a lot more carrier bearing failure with synthetic oil. Not sure which way to lean on this one.
 

nhdiesel

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Milan, NH
I'm no professor, scientist, or really an expert in any field. I am a mechanic, and I see all kinds of vehicles with all kinds of mileage. My personal opinion, although it may seem stupidly common sense to some, many people ignore it, is to change your oil on a regular basis and use pretty much any recommended oil for your vehicle. Clean oil is #1 important point, to me more important than what type, brand, etc.

I've seen lots of 300k mile vehicles that have survived on cheap dino oil. I've also seen many vehicles running high dollar synthetics die an early death. One myth I'd like to kill is the extremely long change interval many people still believe is possible with synthetics. WRONG!!! I've seen customer's vehicles with 20k miles on Mobile-1, and it comes out like old gear oil. Nasty, black, and thick. Synthetic is fine, but change it at a reasonable interval!

Here are some of my experiences with my own vehicles and different oil:

-'03 Yamaha RX-1 snowmobile. Bought new, changed oil to name-brand dino at 500 miles. At around 1200, changed to Amsoil. Had been noticing a bit of oil usage since around 700 miles. By 2k miles, I was using a quart every 1k miles. By the 4k mile mark, I was using 1 qt. in 300 miles. Yamaha replaced the engine under warranty (after a long battle with them.)

-'06 Kawasaki KLR650, bought new: Used Rotella synthetic (highly recommended by the KLR crowd for this old, outdated engine) since first oil change. Changed the oil every 1500-2k miles, always used the same oil. After a trip to Kentucky with it this year, it seized on me on my way to work. Bike has around 17k miles.

-'98 Jeep Cherokee, 4.0 I-6. Bought for our daily driver with around 110k miles. Has 160k now, the last 20k being as a trail vehicle with lots of street driving in between. I always used Napa dino oil, changed every 5-6k miles. Runs perfect, doesn't use a drop between changes.

As you can see I haven't had any better luck with synthetic than with dino oil. But where I live it can easily get to -30 on a winter morning, and synthetic is great to have then!

Just my 2cents

Jim
 

Seatyger

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Ontario
X3 on the timely oil changes and regular maintenance schedule when dealing with stock engines/drivetrain. I have no real experience with hi-perf stuff but would certainly want to use the best available. Especially when an engine costs damn near as much as a house!
:twisted:
Interesting topic, appreciate you guys digging this stuff up.

Jim
 

subhunter

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ga
The maximum amount of anti-wear additive (ZDDP) is capped by API/ILSAC depending on viscosity and the API/ILSAC rating of the oil. In general, the API SM oils are going to be capped at 800 parts per million (ppm), while the older API SL allows up to 1,100 ppm. Most of our engine oils have retained an API SL rating and we generally treat at or near the allowable level. The limit for viscosity grade of 10W-40, 15W-40 and 20W-50 have a higher allowable level of 1,200 – 1,300 ppm. The XPR oils contain in excess of 1,900 ppm of ZDDP anti-wear additive.
Thanks for considering Royal Purple and have a great day.

Best Regards, Christopher Barker

Tech Services Royal Purple, Inc.

1 Royal Purple Ln. Porter, TX 77365 281-354-8600

*^*^*^
AmsOil 25k mile oil has at least 1500 ppm
*^*^*^

Hi , Thanks for contacting Spectro Oils

All our 4 stroke oils are 1800ppm zinc and phosphorus. Zinc (zddp) and phosphorus are two critical anti wear additives, sadly many other oil
companies skimp on these due to cost.

Thanks for choosing Spectro!

Rollin Karoll Vice President of Sales Spectro Oils

993 Federal Rd Brookfield, CT 06804 800-243-8645
 
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subhunter

New member
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0
Location
ga
Oil's will drive you nuts. I have seen bad cases where the motors gum up.
I believe its because people run the oil to long or todays cars are running
hotter.
Change your oil often , its cheap insurance.
 
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BLKBRD

New member
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Location
Tulsa, Ok
"Then there is the myth that new engines will not break-in on synthetic oils. Apparently there was an aircraft engine manufacturer who once put out a bulletin to this effect. Clearly the thousands and thousands of cars filled with Mobil 1 as factory-fill, which have broken-in quite well, should have put this one to rest. However, this myth is only 40 years old, so it has another 35 years to live."

Aircraft engines and car engines are different monsters. As an aircraft mechanic of over twenty years. Do what the manufacture of the vehicle you are driving says to do. If your in AC and don't, you get to go to a meeting where everyone gets to eat donuts but you. It can mean big bucks out of your pocket or jail time.

If you have a new car under warranty and something happens to the engine and they find out you didn't follow their maintenace requirments. Sorry it's your problem to fix. They will look for any reason they can find to not cove it.

But do as you want as an adult you can, but you have to pay the price.
 
I'm no professor, scientist, or really an expert in any field. I am a mechanic, and I see all kinds of vehicles with all kinds of mileage. My personal opinion, although it may seem stupidly common sense to some, many people ignore it, is to change your oil on a regular basis and use pretty much any recommended oil for your vehicle. Clean oil is #1 important point, to me more important than what type, brand, etc.

I've seen lots of 300k mile vehicles that have survived on cheap dino oil. I've also seen many vehicles running high dollar synthetics die an early death. One myth I'd like to kill is the extremely long change interval many people still believe is possible with synthetics. WRONG!!! I've seen customer's vehicles with 20k miles on Mobile-1, and it comes out like old gear oil. Nasty, black, and thick. Synthetic is fine, but change it at a reasonable interval!
Jim
Check out this test: Results of New York City Taxi Test

I use synthetic oil in all my engines from my lawn mower to my Cat 3116. So far, so good.
 
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