ZDDP? and the use in older Z engines

[Poindexter]

Wasn't the original debate about the level of ZDDP during the break-in period?

No. See first post and thread title.

Only mentioned in passing (good info though) in Post #9.

Or do you mean "original" as in throughout recent history as ZDDP came to be used more and known- ±40 years ago? I have seen that idea bandied about. I think it always was intended to be used through the life cycle- but absolute facts are tough to come by.

Edited September 7, 2008 by Poindexter

[doradox]

I think I've already spent enough time looking for the truth that if I valued my time at minimum wage I could buy enough ZDDP to last about 10 years. It has been interesting though.

Steve

[Walter Moore]

You are correct that 1000 ppm is .001%

Steve

Actually 1000 ppm is 0.1%

(1000/1000000)*100% = 0.1%

Somehow the previous quote kept bothering me, so I had to do the math to prove to myself that I wasn't crazy. (Well I may be crazy but I can do basic math)

Also, to quote this previously posted link:

http://www.bobistheoilguy.com/forums/ubbthreads.php?ubb=showflat&Number=1049812

"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."

I suspect that the study he mentioned explains why none of the oils listed on the Mobil-1 chart contain more than 1200 ppm phosphorus.

Everything that I read on this subject comes back to flat tappets. Actually this makes sense, because unlike the L6 motors where there is clearance between the cam and the rocker arm most of the time, on a flat tappet motor the lifter is in constant contact with the cam. This is particularly true in engines with hydraulic lifters. (read American V8s) If you read the thread discussion further, the people who contradict the "debunker" are talking about high lift OHV engines with high spring pressures. (Street rods etc.) Again, those are not an apples to apples comparison to the valve geometry of most OHC engines, and are definitely different from an L6.

To those who are adding extra ZDDP, remember the saying in chemistry: "It is the dose that makes the poison." It appears from the quote above that when the phosphorus level in your oil reaches 1400ppm the camshaft will actually wear faster. Phosphorus is corrosive itself. Too much ZDDP is apparently worse than too little.

Just trying to be helpful.

[doradox]

Actually 1000 ppm is 0.1%

(1000/1000000)*100% = 0.1%

Forgot my units.

Steve

[Poindexter]

What I meant was that 1000 ppm = .001 in decimal, not percent. That's how many of the manufacturers state component weights.

Edited September 8, 2008 by Poindexter