While we may never know for sure if this particular failure was oil-additive related, it does show what can happen when the contact surfaces of lobe and lifter wear past the break-in polishing. Both the cam and lifter were high-quality, name-brand units. Break-in and normal use included top-quality synthetic oil that met the latest standards.
What This Means To Us
From its operational characteristics, the camshaft seems as though it benefits most from ZDDP. But modern engines like the LT1, the LS1, and the LS2 used in late-model Firebirds and GTOs have lifters with roller bearings, which greatly reduce frictional contact on the lobe. Because of this, it appears roller camshafts have been largely unaffected by the oil changes. It is, however, an entirely different story with flat-tappet camshafts.
The recent spike in reported flat-tappet camshaft failure seems to be consistent with the enacted ZDDP restriction. While some could argue that lobe profile or a decline in camshaft hardening is to blame, that argument may only be valid if several lobes of the suspect cam were affected. It would, however, unlikely be the case if the problem is limited to a single lobe. That then might indicate an issue with a specific lifter, its preload setting, or insufficient lubrication.
Since proper camshaft break-in is such a critical step in ensuring its longevity, most camshaft manufacturers are suggesting physical steps or specific products for break-in. But some have recently begun advocating certain products for long-term use, too. These include those oils approved for commercial-fleet vehicles and/or separate oil additives that are currently available from mail-order retailers, local parts stores, or GM dealers.
Available from GM dealers for about $10 per bottle, Engine Oil Supple-ment (E.O.S.) carries PN 1052367 and is a highly concentra-ted mixture of several key oil additives. It is designed to protect against piston scuffing and camshaft wear during the break-in period. But because of its heavy zinc and phosphorus content--which is advertised at no more than 5 percent by weight--and the increased risk of catalyst failure from it, GM officially advises that E.O.S. is not intended for long-term use.
Because commercial-rated and service-rated oils fall under different standards, oils approved for commercial use typically contain more of the desirable high-pressure, antiwear additives. Since many commercial-grade oils have older S- or GF-category ratings, oil companies claim it is safe for use in gasoline-fueled engines, unless catalyst failure is a concern. Commercial-grade oil is also available in synthetic, conventional, or a blend, and may fit a wide range of non-catalyst applications if it is available in the desired monograde or multigrade viscosity.
Race-specific or specialty oils may be another alternative. We have found that many of the lesser-viscosity offerings comply with the latest oil standards. But many higher-viscosity oils are restricted to off-road-use only. This might indicate different levels of ZDDP within each product, which could have an effect on the exhaust catalyst. It would be worthwhile to refer to the oil manufacturer's Web site for more detailed information on specific products or category ratings.
We highly suggest that hobbyists familiarize themselves with the quality standard and category rating information found on API's Web site. It not only discusses current standards, it also shows how to decipher the API "donut" printed on each oil container's label. We also suggest reviewing or requesting the latest Material Safety Data Sheet (MSDS) from your preferred oil's manufacturer. This information, which is oftentimes available on the manufacturer's Web site, is an invaluable resource that specifies an oil's API rating and chemical content.
Most GM engines from about 1987 forward have hydraulic lifters with roller bearings that greatly reduce frictional contact. Many aftermarket camshaft manufacturers offer similar roller-type camshafts for our vintage Pontiacs. Because these camshafts are typically made of harder material and the roller bearing on the lifter face reduces friction, it appears they are unaffected by the recent oil changes.
Conclusion
If you own a new or late-model Pontiac, much of the presented information may not apply. In that case, simply follow your owner's manual recommendations. If you own a vintage Pontiac with a flat-tappet camshaft and a cata-lytic converter, you may be forced to use latest-standard oil to avoid the risk of catalyst failure. Engine protection, however, may be worth the cost of periodic catalytic converter testing and any necessary replacement. If you feel that it is, the following will apply.
Those of us who have older Pontiacs with flat-tappet camshafts might now realize how much oil formulation has changed in recent years and its effects on the hobby. The best suggestion we can offer is to follow your camshaft manufacturer or engine builder's recommendations for break-in and long-term use. Chances are it will include heavy-duty, commercial-grade oil, or a specific bottle of oil-additive for the life of the engine. Following their suggestions is wise not only for warranty issues, but it should also provide many miles of enjoyment.