Zinc vs. Phosphorous in measuring ZDDP Content

[SnowDrifter]

I've noticed that Zinc and Phosphorous tend to track together in motor oil, however the phosphorous concentration is generally lower than that of zinc.

Just curious... Which one provides a more accurate indication of how much ZDDP is in the oil?

 

[29662]

ZDDP stands for Zinc dialkyldithiophosphates. ZDDP contains both Zinc and phosphorus, so it's a joint deal. You can't have one without the other. So they are both indicators of how much ZDDP is in the oil.

 

[A_Harman]

It is Phosphorous that the API regulates because it is the element that poisons catalytic converters. That is what will limit the amount of zddp in an oil, regardless of what specific type is used.

 

[SnowDrifter]

Yeah I follow you there

My target for ZDDP content is between 1200 and 1400PPM, older car with flat tappets. Ideally as close to 1400PPM without going over. But I'm trying to figure out which of those is a better indicator of concentration.

Or a different approach to the same issue: is Zinc or Phosphorous responsible for camshaft spalling at too-high of concentrations?

 

[userfriendly]

Snowdrifter;
You will not likely get those ZDDP levels with either
SM or SN oils.
A rule of thumb;
Zinc is usually 10% higher than Phosphorous.
A good place to look is CI-4+.

For example Chevron's Delo 400 old school CI-4+
Phos 1350, Zinc 1500.
Petro-Can 15W40 XL Syn blend CI-4 lists Phos at 1300
so I'll assume the Zinc is 1400-1450.

Another rule of thumb with FT cams;
The higher the lobe lift and spring pressure
the higher the minimum idle RPM.
Larger cam cores and lifter diameters are the way to
go with FT cams.
BBF: large cam core and .875" lifter diameter.
BBC: Smaller cam core and .843" lifter diameter.
BBMopar: BBC cam diameter (close) and .903" lifter.

The best combination would be the BBF cam
core diameter with the .903" lifter.

Increasing the diameter of either the cam core
or lifter will add duration to a given
lobe master.

 

[Fraser434]

I did a stint with a pro mod team on the road. They would run AMSoil Dominator 20W-50 and put in 8oz. 'ZDDP' additive, probably close to 2000ppm zinc/phos. They tried LAT oil and burned the pushrods tips, directly related to inadequate amount of Zinc/Phos aka ZDDP. That's what going on in a much lower level in your usual race engine without adequate ZDDP.

I'd like to look more into Boron and Moly, in addition to ZDDP levels for a race engine valvetrain.

 

[userfriendly]

The pushrod tips are the highest loaded valve train
component.
Would any amount of additive prevent them from burning?
If not, then increasing the oil flow to the pushrods
would keep them cooler.
How is AMSoil Dominator 20W50 formulated?
Does it contain VIIs?
Would the engine oils that fuel teams run protect your
valve train better than a multi-grade?

 

[m37charlie]

A nice additive to bump ZDDP levels, also raises TBN about 1 for each 300ppm Zn/P:
http://www.redlineoil.com/product.aspx?pid=121

Charlie

 

[SnowDrifter]

I currently have a bottle of ZDDPlus, though I'm apprehensive about using it until I can figure this out as I don't want to risk too much and cause more harm than good

 

[Fraser434]

Originally Posted By: SnowDrifter
I currently have a bottle of ZDDPlus, though I'm apprehensive about using it until I can figure this out as I don't want to risk too much and cause more harm than good
huh? I added a bottle to my old colorado 3.7L, 6 quarts 1 bottle of ZDDPlus, Zinc/phos was 1500ppm on the UOA, added roughly 500ppm Zinc/Phos to 6 quarts of oil.

 

[SnowDrifter]

That's it?? VOA I found seemed to indicate it was VERY concentrated. Bit of math based on these numbers, seems it would need to be added in the
http://www.bobistheoilguy.com/forums/ubbthreads.php/topics/1137332/1

Seems this thread seems to recommend caution during use as well

http://www.bobistheoilguy.com/forums/ubbthreads.php?ubb=showflat&Number=1600838

 

[m37charlie]

Yes. Fraser 434 increased his phosphorus by about 1600ppm to a dangerous (to the camshaft) 3000ppm. Levels>2000ppm can cause spalling of the lobe metal.
Some people don't believe the old saying "read the directions".

Charlie

 

[SnowDrifter]

If I read between the lines a bit... Phosphorous is what causes damage and should be the one to be mindful of?

 

[MolaKule]

Originally Posted By: SnowDrifter
I currently have a bottle of ZDDPlus, though I'm apprehensive about using it until I can figure this out as I don't want to risk too much and cause more harm than good


Get an analysis of the virgin oil.

Add one ounce of the zddp additive to the quart and do a VOA of the mix to see how much the OTC additive bumps up the total additive amount.

That way, you won't be shooting in the dark.