"If you're currently putting mileage on your classic vehicle and using the latest API grade SM oil, you are almost certainly doing irreversible damage to your engine." 'New Oils and Old Cars', Old Cars Weekly, Issue 48 (30th August 2007)

After 70+ years of trouble-free, metal-to-metal engine protection, the E.P.A. is forcing ZDDP (Zinc Dialkyl Dithio Phosphate = Zinc and Phosphorus) from domestic motor oil. If your engine was designed prior to the 1990s, your non-roller lifters require ZDDP in your motor oil to avoid premature deterioration. Don't let your lifters run metal-to-metal. Keep ZDDP, via ZddPlus, in your motor oil. Add the 113ml contents of this Super Concentrated ZddPlus bottle at every 4.75 litre oil change.

Why Add ZddPlus? What's the History of this problem? Why is it only apparrent now in 2009?
As part of an effort to reduce vehicle emissions, the U.S. EPA offers vehicle manufacturers "credits" for early implementation as well as penalties for violation of emission reduction standards. The EPA's program called for 100,000-mile catalytic converter life by 2004, 120,000 miles by 2007, and 150,000 miles by 2009. To achieve these goals, automotive manufacturers worldwide have pressured their oil suppliers to remove substances from motor oils that would shorten the service life of the catalytic converter, including the proven EP (extreme pressure) additive ZDDP (zinc dialkyldithiophosphate). Zinc and phosphorus from the ZDDP can be present in small amounts in the exhaust gas of an engine depending on the amount of oil which is consumed in combustion. These elements can coat the catalyst reducing the amount of catalyst exposed to the exhaust gases, thereby shortening the catalytic converter's effective life. As a result of the EPA mandate, the ZDDP level in engine oils has been declining since the mid-1990s, allowing car manufacturers to claim extended catalytic converter life.

ZDDP has been an important additive to engine oils for over 70 years, and has an excellent track record at protecting the sliding metal-to-metal cam lifter interface. ZDDP is a specific molecule of a combination of Zinc (Zn) and Phosphorous (P) in the correct ratios. Historically, ZDDP has been added to oils in amounts resulting in approximately 0.15% phosphorus, and 0.18% zinc. ZDDP protects by creating a film on cams and flat lifter contact points in response to the extreme pressure and heat at the contact point. This film of zinc/phosphorus ZDDP provides a sacrificial wear surface protecting the base metal of the cam and lifter from wear. In the course of normal service, this protective activity causes conversion of ZDDP to individual zinc and phosphorus compounds, thus depleting the ZDDP level in the oil. Studies show that depending on the specific engine and severity of duty, after roughly 3220-6440 kilometres of operation, the level of ZDDP can drop below that considered adequate to provide wear protection to the cam and lifters.

According to the SAE tech Bulletin # 770087, operation of a flat tappet engine without adequate EP additives such as ZDDP quickly leads to lifter foot scuffing and cam lobe wear. Camshafts are typically only surface hardened leaving the core ductile for strength. According to the SAE Bulletin, once cam lobe wear reaches 0.0002 inch, "subsequent wear is usually rapid and catastrophic." Two ten-thousandths of an inch is one fifth the thickness of an average human hair.

In order to make engines last in the absence of ZDDP, virtually all IC (internal combustion) engines designed in the last ten years utilize roller lifters. Today, ZDDP has been removed from practically all automotive engine oils, rendering them unsuitable for use with older engines with non-roller lifters.

Motor oil is one of those hot subjects that is always capable of starting a debate among car owners. Most classic engine owners have a particular brand of oil that they feel is the best, and will debate the merits at length with anyone. But this latest debate among vintage car owners over the elimination of ZDDP is widespread and touches everyone interested in motors designed more than 20 years ago. You see, for most of the last century, the almost universal method to open and close engine valves was via flat tappets (with solid or hydraulic lifters), and the ZDDP additive was there to prevent or reduce wear between the lifters and the camshaft (#6 and #7 respectively in the diagram to the left). This also happens but to a lesser degree (due to curved wear surfaces which spread the load over wider areas), on the interface between the pushrod and rocker arm (#3 and #5) and also between the rocker arm and valve stem (#2 and #1) in the diagram. But ZDDP in the minute amounts of oil that will get burned and exit through the exhaust system will shorten the life of catalytic converters. Thus the EPA mandate to eliminate ZDDP from engine oil, and the auto makers have responded by designing engines that utilize roller lifters or overhead camshafts, and have no need for the protection offered by ZDDP.

Why is it being removed? Because contemporary engines with roller bearings no longer require the additional protection of Zinc and Phosphorus. Not true for classic cars, tractors, muscle cars, etc. Also removing the Zinc and Phosphorus from motor oil increases the life of the catalytic converter. But classic cars, tractors, etc., don't have catalytic converters! Also, as part of its ongoing effort to reduce vehicle emissions, the EPA has mandated that emission systems must have a service life exceeding 120,000 miles. To achieve this, automotive manufacturers have required oil suppliers to remove additive packages from motor oils that could reduce emissions compliance.

ZddPlus is the ONLY EP (Extreme Pressure) component which re-establishes the ZDDP levels that our classic car engines were designed for, while allowing the car owner to use the base oil of their choice. While some off-the-shelf additives may have some ZDDP, the amount per bottle is small, and when enough is used to get the proper concentration of ZDDP, there is a quart or more of unspecified oil that comes along with it. This dilution of 20% of your oil with an unspecified oil also means that there is 20% less of the proper additive package.

What's Already In Our Oil? Which additives do what?
As lubrication technology improves, so does the base oil used in the manufacture of engine oils. Oils are also changed and updated in response to advancements in engine technology.

Modern engine oil is a precise mix of a base oil with additives totaling almost 10% of the oil by volume. Kilo for kilo these additives are each much more expensive than the base oil, and oil companies are in business to make a profit. Common sense says that these expensive additives are there with good reason.

Modern engine oil is a multi-purpose fluid in an engine, carrying the heat away from hot spots and releasing it in the sump as well as providing lubrication to critical areas which need protection against friction wear. Different additives are put in the oil in order to address the needs of each specific engine system that is supplied with oil. Here are some of the reasons additives are put into oils by the manufacturers:

1-Anti Foaming Additive -The crankshaft and connecting rod bearings discharge oil into the spinning reciprocating assembly, and an anti-foaming additive keeps the oil from turning into foam.
2-Stabilisers - The heat developed on high-pressure contact areas can exceed the breakdown temperature rating of the base stock, so heat stabilisers are added in order to fight viscosity breakdown and ashing.
3-Viscosity Stabiliser - In a multi-viscosity oil, the multi-viscosity characteristic is established by an additive.
4-Chemical Neutraliser - Acids and byproducts of combustion are neutralised by another additive.
5-Dispersants - A dispersant additive helps keep combustion particulates from clumping.
6-Detergents - Detergents are added to lower the surface tension to a specific value to help keep contaminants in suspension and off of the metal engine parts. Some detergents also interact with the EP additive to gain an additional level of wear protection.
7-EP (Extreme Pressure) Additive - The sliding cam-to-cam-follower interface in a non-roller lifter engine requires a special EP additive, which has historically been the ZDDP that is now reduced in all API rated automotive oils. ZddPlus contains the proper amount of ZDDP to give at least 0.18% zinc and 0.13% phosphorus level when a single 113ml bottle is added to a normal 4.75-litre oil change. This level of zinc and phosphorus is the level designed into pre-OBDII oils. Using ZddPlus affords you total control over the characteristics of the oil in the engine by allowing you to use the full 4.75 litres of a high-grade automotive oil of your choice, and restoring the correct ZDDP levels at the same time, economically!

What about off-the-shelf additives and supplements? API oils have always been more than adequate for the engines designed when the oil was current. The use of current API grade oils has always been adequate to satisfy car manufacturer's requirements and warranty demands. Historically, with few exceptions, newer API grades have superseded the performance of their predecessors.

The removal of ZDDP has resulted in a clear change to that philosophy. It has never been necessary or desirable to include additives or supplements to any API rated oil to meet car manufacturer's specifications or warranty requirements. In virtually all cases, off-the-shelf additives amount to little more than automotive snake oil. Current additive technology has yet to develop an EP anti-wear agent as effective as ZDDP.

Consequently, if these additives actually had adequate levels of ZDDP, they would be incompatible with modern engines and void manufacturer's warranties.
Due to this unprecedented turn of events in emissions requirements, ZddPlus should not be confused with off-the-shelf additives. ZddPlus should be considered a replacement for a missing oil component critical for older cars. It's a genuine 'Oil Restorer' not just another snake oil additive.

Certified Test Results
Here's the results panel of a recent laboratory test providing a comparison of commonly available additives and their ZDDP levels. The higher the "Result Zn/P" value, the better the ZDDP levels:

Current additive technology has yet to develop an EP anti-wear agent as effective as ZDDP
Why Add ZddPlus? ZddPlus is not a typical oil additive. By adding a small 113ml bottle of Super Concentrated ZddPlus at every oil change, an adequate amount of Zinc and Phosphorus, in the correct proportions will continue to protect your classic engine, for the service life of the oil in your engine.

ZddPlus simply maintains the Zinc and Phosphorus that has recently been removed.

FAQ - Frequently Asked Questions

Why Can't We Use Diesel CI/CJ-4 Rated Oils?
There are some diesel engine rated oils on the market which may still have some ZDDP in them. There are problems associated with using these oils in a normal petrol engine which can become severe in a high-performance petrol engine. One issue is the high amount of detergent additive, and another is the high viscosity.

High detergent oil has a lower surface tension and lower shear pressure rating which can cause higher bearing wear in petrol engines. A diesel engine needs oil with very high detergent capabilities in order to hold the large amount of combustion byproducts in suspension, but it is not optimized for a petrol engine. The bearing journal size-to-displacement ratio on a petrol engine is designed around the use of a lower detergent oil and relies on a high-shear rating to the oil.

The other problem with high detergent oil is that it actually reduces the friction reduction that the ZDDP affords, especially in a high-performance, high valve spring pressure engine, especially racing engines, aircraft engines and high revving high performance street car engines.

The viscosity rating of most diesel rated oils is higher than optimum for our higher revving petrol engines, and can cause oil starvation in bearings at high rpms.

Why Can't We Use Racing Oils?
There are some racing oils which maintain a level of ZDDP. Racing oils are optimized for short term severe duty, in contrast to an oil that has been designed for day in, day out street operation. The additive package in a racing oil does not have the same detergent characteristics which are designed into extended service oils. As a result, racing oils may not have the capability of neutralising acids and keeping contaminants in suspension. Also, the breadth of choice of viscosity, so important to correct street engine operation over a broad temperature range, is not available in racing oils.

By using ZddPlus in addition to a modern high-quality oil of the proper viscosity for your petrol engine, the correct EP lubrication level is established, and the oil characteristics remain optimized for your engine. This means you can continue to use correct viscosity engine oil of your choice, and by adding one bottle of Super Concentrated ZddPlus you won't need to compromise on the quality, service life or risk dilution of the OEM additives supplied inside your oil.

What is ZddPlus™?
ZddPlus is an oil supplement that contains very high concentrations of the well-known additive ZDDP (Zinc Dialkyl Dithiophosphate), which has been the primary EP (extreme pressure) ingredient in all quality motor oils for over 70 years. However, beginning in the late 1980s, the concentration has been greatly reduced as newer oil classifications have come on the market.

Why do I need ZDDP?
The EPA has put stricter emission requirements on new cars that influenced manufacturers to remove ZDDP from motor oils. If you have an older car that was specified to use SF (1988) or earlier motor oil, its design requires ZDDP. Your older performance car could be damaged with the use of modern SM oils prevalent today. Cars equipped with flat tappet cams need ZDDP because of the high-pressure points. Newer cars have roller rockers and ZDDP is not needed in those applications.
What do the oil grades such as "SF" indicate ? In the API (American Petroleum Institute) classification system, "S" and "C" are the two basic application categories of oil. "S" is intended for petrol use and "C" is intended for diesel use.

"A" was the first grade in each category and resulted in "SA" and "CA" grade oils. Each designation progressed farther up the alphabet as new grades of oil were introduced. The newest grades are "SM" and "CJ" respectively. "SF" was for 1988 and older engines.
Aren't the newer oils better than the older oils? Historically, every new grade of oil introduced since the 1930's was better than the previous grade and could be considered "improved" with one exception. The original SA grade was straight mineral oil (non-detergent non-additives) and SB contained additives which could not be used in the earliest cars specified for SA. While it is true that SM oils are better for NEW cars, they are NOT better for the OLDER cars equipped with flat tappet camshafts. Simply put, the newer, better oils are not backward compatible for older cars primarily due to the gradual reduction of ZDDP starting with SG grade introduced in 1988. In the next few years, it will be eliminated completely from oil.

How much ZddPlus should I add to my oil?
One bottle of ZddPlus will raise the ZDDP concentration level of SL or SM oil to the standards that were in place when SF (or earlier) oil was specified. (SL and SM is the current category available today).
What if my oil already has some ZDDP? ZDDP is most effective if the concentration is between 0.18 and 0.2 % by weight. Tests have shown that concentrations above this amount, up to as much as several percent, have no effect except to prolong additive life. The current oils available today contain very little ZDDP.

Can I use ZddPlus with regular or synthetic oils?
Yes, ZddPlus should be compatible with all conventional and synthetic oils intended for automotive use. Virtually all of these current oils have had some amounts of ZDDP for years, and it continues to be decreased in available oils.
What is the shelf life of ZddPlus? The shelf life of ZddPlus is essentially the same as regular motor oil (many years), as long as a few conditions are met. The temperature should be kept below 120 degrees F and above 0 degrees. You need to keep it sealed until it is mixed with motor oil. ZddPlus has a tendency to absorb moisture, not unlike brake fluid. Absorption of water will degrade its performance, although heating it above 100°C until it is not cloudy will restore it.

When should ZddPlus be added?
Anytime, but the best time is when you get the oil changed. A single 113ml bottle is the correct concentration for a 4.75-litre oil change. This will bring the oil back to SF specifications.

How long does ZddPlus last?
ZddPlus is a sacrificial additive, meaning that in the process of working, it is depleted. ZddPlus should last the life of a normal oil change as specified by the manufacturer of the car, but attention should be given to the categories of service known as "normal" and "severe" conditions. Severe includes stop-and-go driving and short trips, which result in shortened service life of not only ZddPlus, but also most of the other additives in the oil.

Why haven't I heard more about this problem?
The general public, as a rule, has nothing to be concerned about. The people that need to be concerned are owners of older classic cars and performance cars. After the SF category, the amount of ZDDP has gradually been reduced as each new API category is introduced. Had ZDDP been removed completely after 1988 (SF), the scramble for an alternative would have been a big concern. But, since it happened gradually, the concerns were not so obvious.

Why should ZddPlus not be used in OBD cars?
The key ingredient of ZddPlus is ZDDP, which has been known to shorten catalytic converter life. Manufacturers have been redesigning engines for the last decade to minimize the need for ZDDP, in order to lower emission levels. One method is switching over to roller rockers.

Why not just use diesel rated oils, since they contain higher levels of ZDDP?
Diesel engine requirements are much different that those of petrol engines. The higher speeds and lower bearing surface-to-power ratios of petrol engines require oil with higher shear ratings than most diesel oils. Diesels also have higher bearing clearances and that calls for higher viscosity oils. The additional detergents required for soot control actually reduce the effectiveness of added levels of ZDDP found in diesel oils. Also, newer diesel oils beginning in 2007 have greatly reduced their content of ZDDP.

What about the additives offered by the cam manufacturers?
Some of the "Break-in" or "assembly lubes" offered by cam manufacturers contain marginal amounts of ZDDP while others offer virtually none. In most cases these products are intended for initial run-in and rely primarily on other additives such as MDS (molybdenum disulfide). These products, normally added by the engine reconditioner or specialist cam manufacturer are seldom recommended for continued use and most are intended to be removed before the engines are put into service, normally at the first 1000km service after the engine has been 'run-in'.
What about off-the-shelf oil additives? Automotive engines have always been designed and warranted to work properly with the current available oil at the time of manufacture. There has not been a single off-the-shelf additive shown to perform any beneficial function except financial gain to the additive seller. Unlike other additives that have never been recommended by manufacturers, ZddPlus is a replacement for the long-used component of oil that manufacturers once required, but over the years have been forced to remove from the oil for the benefit of newer cars at the expense of older cars.

What about the claims of the various additives?
The performance record of ZDDP is well established. We make virtually no claims for ZddPlus, EXCEPT that it restores the EP (extreme pressure) function of the oil to the level originally required for your older car. Other additives make claims so ludicrous; they cannot be accepted based on common sense. If the claims attributed to most additives were even partially true they would have been part of the standard crankcase fill directly from the manufacturers like ZDDP has been for decades.

Where can I learn more about ZDDP?
A quick search of Yahoo or Google will immediately provide one with numerous sites that deal with this subject. Most sites are credible although many date back several years to a time when things were not as critical as they are now in 2008. For more information, technical reports, original, entire Lab Test reports and technical queries, contact the sole authorised importer for NZ and Australia.