The Stovebolt Site Forums The Shop Area Engine Shop Zinc and flat tappet engines.

I have been following the problems associated with the removal of the zinc from the latest generation of motor oils. Can someone define what makes it a flat tappet engine? Thanks

Flat tappets are the old style that don't have rollers on them. There's more friction associated with a flat tappet system and the cam profiles are generally flatter as well. Roller cams have - as the name implies - rollers, which impart less friction, so the cams can therefore have a sharper profile, leading to faster opening and closing events. Zinc (ZDDP to be precice) has a ton of shear-value whcih is critical on metal to metal flat tappent systems.

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Ron,

I run diesel engine oil which contains the ZDDP. However, it seems that the Zinc is far more critical when breaking in new cam/lifters in our old engines with flat tappet bases. After the engine cam/lifters are broken in, it seems that the continued use of oils with ZDDP (or, the use of a ZDDP additive) is not so critical (but it does not hurt).

I agree with Tim as I use Shell Rotella with an additive. It is probably super overkill, but its worth it in my opinion.

Here's something I found on "Bob-is-the-Oil-Guy" site. take from it what you will...

ZDP Discussion

"OK, first off, yea, i'm sceptical too but this came from a reputable source and is claimed to be a customer service bulletin put out by GM to address some oil "myths". Give it a read and see what you think.

Mark


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"

While I agree that new oils are fine for older engines that are already broken in, it is preferable to have a hight level of ZDP (zinc) in the oil during the crucial break-in phase of a new camshaft and lifters. Sometimes, new oil standards works fine, sometimes it doesn't...I witnessed new cam failure on a fresh rebuild a couple years ago. We primed the oil pump, started up the engine and went straight to a fast idle intending to keep it there for about 20 minutes. About 10 minutes into the run, the engine died and lost compression on all cylinders. Culprit was a failed camshaft. Not positive what caused it, but from now on I will make sure that the break-in oil has ZDP in it.

Thats a good artical you have there Tom, it explaines a lot.
But what it doesn't take into consideration is the new extreme ramp camshafts that have come out in the last 7 to ten years. These are the cams that need as much zinc as you can throw at them. Older stock engines, high performance OEM's excluded, need only standard motor oil meeting todays standards. Try that oil in a hopped up engine with a fast ramp cam, you won't get very far before the cam is smooth. Increase the valve spring pressure over a stock, and you get the same results, smooth cam!

Stock engines all ready broke in need only clean oil. But, if you are starting one with a new cam or fresh rebuild or cleaning, you better have some added zinc. At only $15 a bottle for Comp Cams additive, thats pretty cheap insurance.

I won't start a new engine unless it has cam grease, break-in oil, zinc additive, and been primed a few minutes before starting. Crane Cams and Comp Cams both have excellent information on break-in and oils on there web sites. I have
talked with guys at Butler custom cams, and they say you can flatten a cam in the first 30 seconds of start up if the engine is not prepped right. The first few rotations are the most important, so rotating the engine by hand can start the proccess if you are not carefull.

All the High Performance cam companys will tell you not to use synthetic oil for break in, for one its to thin, and two, it doesn't have enough additive. A few of them will void the warrenty if you synthetic oils! As soon as the engine fires, it should be turned up to 1800 to 2000 rpm, no messing about tuning, get the rpm up. The reason is splash oiling of the cam lobes, thats the only way it gets oil, and at idle its not enough for a new cam even with zinc added.

Joe

this is what crane cams says about synthetic, which is neither too thin or not enough additive.

This is copied and pasted from an email sent
to crane cams
(Hello,
Yes, synthetic oils do not provide the proper interface between the parts that are attempting break-in.
Flat tappets for instance, do not get the traction needed to initiate the spin necessary for proper break-in.
Thanks,)

THAT is why you don't use synthetic to break in a cam it is too slick. this is merely my theory, but I also believe this is one of the basic reasons they went to roller cams in so many of the new engines, not to mention the fuel consumption.

as far as film thickness, the new modular ford (mustangs) have their main bearing clearances at a target of .0003-.0005 that is a half a thousands or less, there is an IRL engine (I don't know which one, the article did not mention it), has the clearance at zero. in this case most likely only a synthetic would provide adequate film strength.

I do know that I work in a heavy industrial atmosphere, and we use lots of gearboxes of varying sizes, and some of the manufacturers of course give the torque rating that can be put through their boxes, with the note that says you can safely increase the torque rating 25% if you use synthetic oil.

as you read in the article the zinc levels are at the level that started all this in the first place. even back then you used a break in lube. There is nothing new here. And given the fellas credentials I tend to believe his version of the story, since he was/is one of the people who actually conduct these tests for our beloved GM (I say OUR beloved, because don't we still own half of GM or some nonsense like that?)

Brokenhead, I agree the oil probably is the same as it was "back then", but the cams in question are not! The designs have changed a lot over the years with fast ramp technology, higher lifts, much greater valve spring pressures, and even the material they are made from. If you are dealing with a true stock, old style engine, no high performance what so ever, then yes, the oils of today will be all thats needed.

When a oil type really matter is with a new high performance cam with much more lift, greater spring pressures, and fast ramps. These are the cams that need zinc. Comp cams Extreme Energy is a good example. In a cam cycle, 720 degree's, you only have so much room to get a valve open and closed. If you can slam the valve open as quickly as possible and slam it shut as fast as possible, you can increased the total valve open time considerably. Where as a slow ramp, such as used "back in the day", the valve was open just as long, but not open as much at each end of the cycle. It might takes as much as 30 to 40 degrees of rotation to get a old style cam lobe to .050" lift, where as todays cams can do it 15 or 20 degrees of rotation. It also takes a valve spring with a high spring rate to control that much lift in such a short amount of room, and along with that comes extreme lifter to cam contact pressure.

I am a firm believer in thin oil, I run a 5W20 in my 250, and Dad runs 5W30 in his 469 inch Pontiac, both synthetics. My local NAPA sells a 0 weight oil for some import cars! I just won't use one for break-in. I like mid weight oils, thick enough to hang on parts, but not so heavy it can't be thrown around.

Joe

The only problem I can see is that there are at least 2 companies (Valvoline and Royal Purple) that are manufacturing full synthetic break in oils. I suppose Crane may not have tested those new break in syntetics yet, as they are fairly new on the market.

I spent much of the day researching this, and I am no closer to a conclusion than I was before I started. I got very little information that agreed with any other information. I did find out though that there is a whole lot more to it than just zinc. The whole oil "recipe" plays various roles in obtaining the fuel economy, emission standards. Even the amount of detergent, and which type of detergent can affect the load capacity of the oil. I found cam companies that said only use 20 or 30 weight non detergent oil for break-in, some say 30 or 40 weight, some say 10w30 is fine, some say never use multi grade. As far as those break in oils mentioned above, are you sure these are intended for a flat tappet engine? There are very few if any engines produced since around '97(?) with flat tappets. (that is something else I found out) All I can really find out is they say you must have the "proper amount of zinc" with multitudes of various proprietary formulas for sale. I had just gotten to the part of what the actual amount of zinc is considered "proper" when I had to stop. I have a stinking suspicion there will be considerable disparity in this arena as well.
As far as crane cams go, Harvey Crane was fired from his company, and crane is now basically S&S cycle, which as you may or may not know caters mostly to Harleys. And (this will probably get a few remarks) Harley seems to be quite behind the times. (I don't care for Harleys)

You can put oil in the same file as brake fluid type and gasket sealer. No matter what you read or how long you look, you will never get the same answer twice!

I have a system that works for me, I built four engines just in the last few months and all four are still running strong, each one was a complete rebuild. I been building engines for close to 30 years and raced for half that long, which means engine tear down once or twice a year for inspections or repairs, dad is still messing with engines and he's 78 years old! Todays engines cost way more then the same one did 10 or 15 years ago, so adding the best oil and as much additive as I can is cheap insurance thats its going to work right the first time. The alternative is a roller cam conversion kit of some sort, a for the Pontiac V8, thats about $2500! So $7 or $8 a quart oil looks pretty cheap.

In 2004 dad wrote a book on building Max Performance for the Pontiac V8, its one of the top selling books for Pontiac engines. When writing this book, we got to talk to a lot of engine builders and parts venders. He still talks with some of them and keeps up on the latest happenings so our information comes from the company guys that make and use the products, not the sales department.

Go at this with a open mind, talk with the guys that deal with it everyday, and pick a company you trust. Theres a hundred ways of doing the same job and if you find one that works for you, stick with it. Find a local dyno shop, they will be able to tell you which oil works or doesn't!

Joe