Bill Verburg

You are totally misunderstanding case wrt ZDDP

There are two main industry oil qualification systems. These are API/I LSAC from USA and ACEA from Europe. Both of these systems are developed jointly between the oil industry and vehicle manufacturers. The updates reflect the latest requirements for standard vehicles and applications. The biggest influence most recently is the “Tier 2” emission regulations in the USA and Euro 4 in Europe.

Standards for engine oil are set by the American Petroleum Institute (API) and the International Lubricants Standards Approval Committee (ILSAC). Prior to 1988 API SF specified a minimum of 1500 PPM P. In 1993 API SG reduced reduced the minimum to 1200 PPM, and it was reduced again to 1000 PPM with the SL specification. A broad wave of flat-tappet camshaft failures started in 2004 following introduction of API SM and ILSAC GF-4 oil specifications which set a maximum of 800 PPM and a minimum of 600 PPM P for grades SAE 0W-20, SAE 5W-20, SAE 0W-30, SAE 5W-30 and SAE 10W-30


The US petrol classifications have two types, ILSAC grades for GF-3, GF-4 etc. are; SAE 0w-30, 5w-30, 1 0w-30, 0w-20, 5w-20 and the rest, not ILSAC. The ILSAC requirements require improved fuel efficiency and have chemical limits on Phosphorus and Sulphur. API performance qualifications started at SB in the 1930s, currently the highest API petrol engine specification is SN. ACEA specifications are A1/B1, A3/B3, A3/B4 and A5/B5. ACEA C1, C2 and C3 are newer low Phosphorus specifications.

So Only ILSAC & ACEA lightweight oils used in newer cars are subject to the regulation.

The heavier weight oils are formulated per the manufacturer's desires, most have reduced ZDDP to a point but that point varies greatly.

The oils subject to the mandatory ZDDP reduction can be recognized by reading the able specs or just noting the symbol. If the symbol is the newer "Starburst" it is regulated oil if the older "Donut" label it is not regulated, note that no heavier weight 15w-50 oil is regulated.

Older APIDonut label


API Starburst label




Here is a history of the ILSAc classifications, at the left is the older API donut label you are looking for



Here is a history of worldwide M1 15w-50 spec
M1 API SH 15w-50 circa '93-96 1095ppm P, 1427ppm Zn(I don't have the specs for previous years but they would have been in line w/ the SH specs)

M1 API SN/SM current 1200ppm P, 1300ppm Zn


Again the issue arose @ ~1000ppm, I wouldn't use an oil below that level. Neither would I use an oil from a manufacturer that won't publish tha ZDDP content of it's oil, which unfortunately rules out a lot of them.

Lastly not all flat tappet engines need the same levels of ZDDP, initial testing for the SJ standard that showed the new oils would still have acceptable ZDDP for flat-tappet cams was done with very mild cam profiles and very low spring pressures. This is not what is found in even a mild performance engine, but may work - or at least appear to work- in older stock-type engines that don't see hard driving, have mild cams and tired valve springs or just see very few road miles - hence the perspective for some that ZDDP levels are not a genuine issue. Each needs to assess the risks and costs and determine their best choice. Note that as an additive ZDDP loses potency over time, losing approximately 1/2 of it's effectivness at approximately 6,000 miles. The latest API SN and ILSAC GF-5 specifications do not change the maximum/minimum ppm ZDDP.

Mobil does publish the info for all it's oils, look here

summary
• Flat-tappet cam failures started with the reduction of ZDDP < 1000 PPM.
• Based on this, 1000 PPM ZDDP is the minimum required level.
• Levels of 1200-1400 ppm ZDDP may be required for more extreme cams. What level defines too much ZDDP is unclear, but for street use more than around 1400 PPM is likely not appropriate.
• Oil change intervals should be no more than ~3,000 miles with dino oil, ~6,000 with synthetic.
• Any oil marked API SM/SN, ILSAC GF-4/5 or ILSAC CJ-5 in grades SAE 0W-20, SAE 5W-20, SAE 0W-30, SAE 5W-30 and SAE 10W-30 cannot have sufficient ZDDP.

Steve Weiner-Rennsport Systems

VERY nice, Bill! Thanks for doing that.

We strongly recommend nothing but API SJ/SH oils for air-cooled engines as we've seen the consequences of using the SL/SM/SN ones.

ToSi

^^ Flat tappet talk might be relevant to a small block Chevy or other OHV engines but none of the Mezger based flat 6 variants use that type of valvetrain. Stick with A3/B3 or Porsche A40 spec & you'll be fine.

-> https://rennlist.com/forums/993-foru...l#post12137062

Steve, how do valve spring rates and seat pressures compare of stock vs the raciest of your custom build offerings? What's the max pressures you see over the sliding rocker pad?

Bill Verburg

All tappets slide across the cam lobe, for the purposes of oil discussions you mostly differentiate between flat and roller. It's not necessary to get into the radius of curvature aspect

there only 2 basic tappets types - flat and roller, each has 2 basic sub types - solid and hydraulic

most if not all flat tappets aren't really flat, most have a radius of curvature

the contact patch almost always approximates a line segment, which slides across the cam lobe

Bill Verburg

Not all aCEA A3/B3 is going to be an oil that is among the better choices

For example and sticking w/ Mobile oils
M1 FS or FSx2 0w-40 is A3/B3 rated and was indeed recommended by Porsche for many years but its P content is 1000ppm and Zn is 1100 this is right on the edge of acceptable and my be below the edge w/ happier cams

M1 high milage 10w-30 or 10w-40 are also A3/B3 rated but again P & Zn @800/900 is below acceptable levels


M1 15w-50 P/Zn @1200/1300 is right where you want in terms of P/Zn and weight

ToSi

It's absolutely significant - think of the difference between a ball vs roller bearing.. point loads are significantly different. Again, aircooled 6's do not have flat tappets.

you assume those 2 numbers define an oil's capabilities.. there's more to the chemistry than just that. Fortunately a marketing whiz developed the A40 specification to help guide the rest of us.