I know higher ZDDP is needed for flat tappet cams especially those that are performance driven. However, is ZDDP say around the 1200 to 1300 PPM needed for push rod engines in general as more friction exist vs having an over head cam design?
ZDDP
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In for answer... I have two pushrods and never even thought of any question like this. Really not going to change my oil based on answer, but always in for ZDDP knowledge, for an unknown reason...
Probably not. I think it’s mainly for flat tappet vs roller lifters not pushrod vs overhead cam. A pushrod engine with roller lifters doesn’t require high zddp where as an ohc engine with really high valve spring pressure may. 
I’m not sure
I’m not sure
The pushrod/lifter/rocker arm interface does like ZDDP, but doesn't need a lot. The 600-800 ppm is fine unless you're a Pro Stocker moving heavy parts across a 2.2:1 rocker ratio with >1.2" lift at 10,500 rpm.
Let's also clear up some language. You are probably talking about zinc content, not ZDDP. You won't know how much ZDDP is in an oil but you may know how much Zn there is. Further, it's really phosphorus that is important, not zinc. The two come together but the Zn ratio can differ by ZDDP type, so a fixed level of Zn my represent a different P level.
ratio can differ by ZDDP type, so a fixed level of Zn my represent a different P level.
The problem with looking at UOA, or VOA, or any result of a chromatograph, is they only report the elements involved.
Not the compounds. Not the actual additives. Not how they work together. Just the elemental parts.
It‘s like looking at a paragraph of writing, counting up the number of times each letter in the alphabet is used, without reading the text, without even knowing the words themselves!
…and then declaring that this must be good writing based on how many times a particular letter is used.…
Not the compounds. Not the actual additives. Not how they work together. Just the elemental parts.
It‘s like looking at a paragraph of writing, counting up the number of times each letter in the alphabet is used, without reading the text, without even knowing the words themselves!
…and then declaring that this must be good writing based on how many times a particular letter is used.…
Shim under bucket SOHC are usually partially bathed in oil on the good designs, so they benefit form an oil wedge, Finger follower DOHC 4V have very light over the nose pressures, due to the low mass that is being accelerated and controlled.
What may be most vulnerable are stamped rocker and pushrod designs where an enthusiast/hot rodder has installed a modern fast ramp cam and kit seeking over 1 HP per cu/in out of a 2v head. There are high forces on the rocker tip, valve stem and on the cam ramp and nose. These designs have marginal oiling, and often times the owner has installed aftermarket valve covers that dispense with needed drip rails on some designs. Even fairly modest cams have been eaten up in the 70's and 80's running highly doped ZDDP oil of the era due to design and material issues. I have rebuilt many of these. If you address materials and oiling you could expect a longer service life, But do not expect high power density engines to have the service life of 1/2 horsepower designs.
- Ken
question is, why just zinc?
yes it does help also as antioxidant. but for friction purpose are better chemistry.
me thinks, if i can save some zinc, by using tungsten instead on friction surfaces, then zinc can last longer, and may keep doing his other roles.
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Higher ZDDP is not needed for flat tappets/cam over bucket/sliding follower. What warrants the increase in ZDDP levels are higher spring pressures in conjunction with those setups, which puts a greater demand on the sacrificial layer established to prevent wear.
A roller engine (be it roller follower, roller lifter...etc) doesn't have that problem because nothing is sliding, so standard levels are just fine with a roller setup.
So, an '82 F-150 with a stock hydraulic flat tappet stick in it, or an RV cam in a restomod, neither of those things requires anything more than standard levels. Fire in a Lunatti Voodoo and the springs it is going to need and that changes the game entirely and you'll be wanting to look for something more heavily fortified, which, the last time I used those sticks, was an HDEO (15w-40) but you might get away with a full-SAPS Euro lube like M1 0w-40, which is designed to handle high RPM sliding followers for extended durations.
Interesting graphs, it shows Moly (Di & Tri), Tungsten and Titanium Oleate, I wish they had also included one or two ZDDP compounds in their tests, sort of as a historical baseline to compare the other compounds to.
BTW back in the 90's I remember buying oil fortified with Tungsten, it cost a few dollars more, but it was considered the good stuff. First oil change in my Holden HJ Kingswood, as I drove off into the Outback.
Really good info. Thanks. I'll stick with maxlife on my 08 Jeep.
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Paging @High Performance Lubricants for input, as I asked this very question as well.
Take this with a grain of salt as it's Vanderbuilt's advertisement, however I'm convinced
Vanlube W-324 is great stuff and I wish it would be more widely used, but it perhaps is
pricey. I wonder if on that testing there's some ZDDP present simultaneously. I'd guess
it is. Does Vanderbuilt provide some details? Engine oils with Vanlube W-324 are what I
use almost exclusively for some years. Remember tungsten commonly isn't used alone.
Such oils have also some Mo and B along with W, and of course varying doses of ZDDP.
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