The ZDDP debate

[chookchakchenes]

GM vs Porsche rebuilder . Sino ang dapat paniwalaan. (post number 2 ang porsche)


GM debunks ZDDP myths for flat tappet cams - Bob Is The Oil Guy

Over the years there has been an overabundance of engine oil myths. Here are some facts you may want to pass along to customers to help debunk the fiction behind these myths.

The Pennsylvania Crude Myth -- This myth is based on a misapplication of truth. In 1859, the first commercially successful oil well was drilled in Titusville, Pennsylvania.
A myth got started before World War II claiming that the only good oils were those made from pure Pennsylvania crude oil. At the time, only minimal refining was used to make engine oil from crude oil. Under these refining conditions, Pennsylvania crude oil made better engine oil than Texas crude or California crude. Today, with modern refining methods, almost any crude can be made into good engine oil.

Other engine oil myths are based on the notion that the new and the unfamiliar are somehow "bad."

The Detergent Oil Myth -- The next myth to appear is that modern detergent engine oils are bad for older engines. This one got started after World War II, when the government no longer needed all of the available detergent oil for the war effort, and detergent oil hit the market as “heavy-duty” oil.

Many pre-war cars had been driven way past their normal life, their engines were full of sludge and deposits, and the piston rings were completely worn out. Massive piston deposits were the only thing standing between merely high oil consumption and horrendous oil consumption. After a thorough purge by the new detergent oil, increased oil consumption was a possible consequence.
If detergent oils had been available to the public during the war, preventing the massive deposit buildup from occurring in the first place, 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 many years for an oil myth to die.

The Synthetic Oil Myth -- Then there is the myth that new engine break-in will not occur with synthetic oils. This one was apparently started by an aircraft engine manufacturer who put out a bulletin that said so. The fact is that Mobil 1 synthetic oil has been the factory-fill for many thousands of engines. Clearly, they have broken in quite well, and that should put this one to rest.

The Starburst Oil Myth -- The latest myth promoted by the antique and collector car press says that new Starburst/ API SM engine oils (called Starburst for the shape of the symbol on the container) are bad for older engines because the amount of anti-wear additive in them has been reduced. The anti-wear additive being discussed is zinc dithiophosphate (ZDP).

Before debunking this myth, we need to look at the history of ZDP usage. For over 60 years, ZDP has been used as an additive in engine oils to provide wear protection and oxidation stability.

ZDP was first added to engine oil to control copper/lead bearing corrosion. Oils with a phosphorus level in the 0.03% range passed a corrosion test introduced in 1942.

In the mid-1950s, when the use of high-lift camshafts increased the potential for scuffing and wear, the phosphorus level contributed by ZDP was increased to the 0.08% range.

In addition, the industry developed a battery of oil tests (called sequences), two of which were valve-train scuffing and wear tests.

A higher level of ZDP was good for flat-tappet valve-train scuffing and wear, but it turned out that more was not better. Although break-in scuffing was reduced by using more phosphorus, longer-term wear increased when phosphorus rose above 0.14%. And, at about 0.20% phosphorus, the ZDP started attacking the grain boundaries in the iron, resulting in camshaft spalling.

By the 1970s, increased antioxidancy was needed to protect the oil in high-load engines, which otherwise could thicken to a point where the engine could no longer pump it. Because ZDP was an inexpensive and effective antioxidant, it was used to place the phosphorus level in the 0.10% range.

However, phosphorus is a poison for exhaust catalysts. So, ZDP levels have been reduced over the last 10-15 years. It's now down to a maximum of 0.08% for Starburst oils. This was supported by the introduction of modern ashless antioxidants that contain no phosphorus.

Enough history. Let's get back to the myth that Starburst oils are no good for older engines. The argument put forth 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 facts say otherwise.

Backward compatability was of great importance when the Starburst oil standards were developed by a group of experts from the OEMs, oil companies, and oil additive companies. In addition, multiple oil and additive companies ran no-harm tests on older engines with the new oils; and no problems were uncovered.

The new Starburst specification contains two valve-train wear tests. All Starburst oil formulations must pass these two tests.

- Sequence IVA tests for camshaft scuffing and wear using a single overhead camshaft engine with slider finger (not roller) followers.

- Sequence IIIG evaluates cam and lifter wear using a V6 engine with a flat-tappet system, similar to those used in the 1980s.

Those who hold onto the myth are ignoring the fact that the new Starburst oils contain about the same percentage of ZDP as the oils that solved the camshaft scuffing and wear issues back in the 1950s. (True, they do contain less ZDP than the oils that solved the oil thickening issues in the 1960s, but that's because they now contain high levels of ashless antioxidants not commercially available in the 1960s.)
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 probably take 60 or 70 years for this one to die also.

Special thanks to GM's Techlink
- Thanks to Bob Olree – GM Powertrain Fuels and Lubricants Group

[chookchakchenes]

This is from LN Engineering, a Porsche engine rebuilder, and they are very vocal about the loss of ZDDP:

Oils: What motor oil should I use? Which oil is best for my Porsche or aircooled engine?

Excerpt:
Many Porsche repair shops have acknowledged that these newest SM and CJ-4 motor oils are not sufficient for protecting any Porsche engine. With longevity and the protection of vital engine components in mind, many shops are recommending non-approved motorcycle or racing oils, or the addition of oil supplements at every oil change, for their higher levels of protection.

Oil companies have been cutting back on the use of Zn and P as anti-wear additives and switching to alternative zinc-free (ZF) additives and ash-less dispersants in their new low SAPS oils since Zn, P, and sulfated ash have been found to be bad for catalytic converters. One such ZF dispersant/anti-wear additive is boron, which does not foul the catalysts in the particulate emissions filters or catalytic converters. For most owners, the reduction in longevity of a catalytic converter is a small price to pay considering the many thousands of dollars it costs to properly rebuild a Porsche engine. It is worth noting that most Porsches have lived the majority of their lives with high Zn and P oils as found in API SG-SJ oils as late as 2004, and we never hear of problems with their catalytic converters.

In addition to protecting emissions controls, there are many other design considerations in formulating engine lubricants, which include improving fuel economy and longer drain intervals. High friction can result in areas with boundary lubrication or where high viscous friction forces and drag may occur with hydrodynamic lubrication in bearings. The use of friction modifiers, such as moly (there are many different species of Mo-based friction modifiers, help to reduce friction in metal-to-metal contact with the formation of tribofilms characterized with their glassy, slippery surfaces. Lower viscosity motor oils are key to increasing fuel economy by their reduction in drag where high viscous friction occurs in hydrodynamic lubrication. While lower viscosities improve fuel economy greatly, they also reduce the hydrodynamic film strength and high temperature high shear viscosity of the motor oil, factors both of which are key to protecting high performance engines, especially aircooled ones.

However, it is worth noting that these new API guidelines do not need apply to “racing,” “severe duty,” or any motor oils that do not carry an API “starburst” seal or clearly state for off-road-use only. Motor oils meeting “Energy Conserving I or II” standards should be avoided as well as those with an API SM or ILSAC GF-4 classifications. The European ACEA A3/B3 classifications, which place a cap on P levels at 0.10-0.12% but allow for higher Zn levels, to be better in taking into consideration wear and engine longevity, setting much lower wear limits, while still limiting emissions and protecting emissions control devices. It is common to find API SJ rated oils, particularly those meeting Volkswagen's stringent 505.01 standard for PD TDI engines, to also meet ACEA A3/B3 requirements. The current ACEA A3/B3 classifications require higher high-temperature high-shear (HTHS) viscosities, stay in grade sheer stability, and tighter limits on evaporative loss (noack volatility), high temperature oxidation, and piston varnish. This makes oils meeting these ACEA standards that much better for your Porsche, especially since wear limits are much more stringent for valve train wear, 1/6th to 1/4th the wear allowed in the sequences for API's newest SM or CJ-4 standards. Of particular interest is the upcoming ACEA E9 standard to supersede the API CJ-4 standard in Europe, creating a classification for low ash oils that are low detergent and are very effective in controlling wear in legacy engines.

Failure to use the right oil, use proper filtration, or observe proper changing intervals can affect the performance of even the best motor oil. This also includes changing the oil too often (needlessly bad for the environment and your wallet) or not often enough. Against conventional wisdom, engine wear decreases as oil ages to a certain extent, which means that changing your oil more frequently actually causes engine wear; these findings were substantiated by studies conducted by the auto manufacturers and petroleum companies, leading to drain intervals increased from 3,000mi/3 months to 5,000-7,500mi/6 months in most domestic vehicles, using mostly non-synthetic oils. Based off of extremely long drain intervals recommended by most European manufacturers, some in excess of two years and 20,000 mi, some users have found it best to reduce those intervals by half or even a quarter. Porsche for the 2008MY has reduced their extended drain intervals significantly to one year/12,000 mi, which is actually less miles than Porsche recommended back in the 1990s with 964 and 993 based aircooled 911s. Based on UOAs provided to us by our customers, new Porsche owners should consider reducing their drain intervals further to no more than 9,000 mi or one year.

Vehicles with track time or sustained high oil temperatures or RPMs should have their oil changed after every event (or every other event). This translates to a total of about 10 hours max, with vehicles with 12 qt or higher oil capacities- engines with smaller capacities must be changed more often. Vehicles subjected to very short drives or sustained operation in heavy traffic should indeed be serviced more often. Likewise, vehicles not driven often but driven hard a few times a year can probably go a year between oil changes, but that doesn't mean you shouldn't use a good oil! Regular used oil analysis is the best way to determine ideal drain intervals for your driving habits - one good rule of thumb I have seen quoted is to change the oil with the TBN (total base number) is reduced by 50% of the original total (requiring you to also know your oil's virgin TBN). Another common recommendation is to change the oil once it's TAN (total acid number) equals the TBN. Other factors to consider are fuel dilution and shearing out of grade when determining your drain interval. With this knowledge in hand, using a quality motor oil with proper filtration and regular service is the best thing to do for your engine and to protect your investment.