Doing the math on zinc additives. How much to add?

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I would like to start using a zinc additive. For now it looks like I will be going with Zddplus. They claim it has 71,800 ppm zinc according to the Zddplus Tech Brief . The oil I will be using has 1100 ppm zinc in it. My engine holds 4.75 US quarts of oil or 152 US ounces. How much Zddplus do I add to bring the oil up to a 1900 ppm zinc level? TIA
 
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43.5 mL or 1.47 fluid US ounces 71800 mg/kg Concentration of zinc product 1100 mg/kg zinc in old oil 1900 mg/kg zinc in new oil 800 mg/kg delta 0.86 oil density 0.99 zinc product density 1.057 qt/L (volume conversion) 4.75 qts 4.49 L 3.865 kg oil in sump 4251 mg zinc total zinc mass prior 7343 mg zinc total zinc mass post 3092 to be added mg zinc 0.043 kg of ZDDP oil to be added 0.043 L of ZDDP oil to be added 43.5 mL of additive add 1.3% for increase in volume ---> 44 mL
 
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I should probably show how I came to that number.... 1900ppm target 1100ppm current --------------- 800ppm addition 71800/800 = 89.75 4.75x32oz = 152oz 152oz/89.75 = 1.6936oz (this is actually very slightly low, since you're increasing the sump capacity by almost 2oz, which reduces the total PPM) Adding 1.75oz even should bring it to 1917ppm 152oz+1.75oz = 153.75oz 153.75oz/1.75=oz 87.857 71800/87.857= 817 1100+817 = 1917
 
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 Originally Posted By: Al
And why would you want to have these higher levels??
That was my question.... Unless you have a flat tappet engine (see link on my signature) it won't do much for you and will risk your catalytic converter. And where is the 1900 target coming from. That is up into the levels that can cause cam damage.
 
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 Originally Posted By: widman
That is up into the levels that can cause cam damage.
And bearing erosion, too. ...and valve deposits. ...and plug fouling.
 
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 Originally Posted By: Al
And why would you want to have these higher levels??
Because everybody KNOWS that today's oil doesn't have enough zinc and that engines will soon become boat anchors. As already said, unless you have either a flat tappet engine or a new rebuild, modern oil is just fine for at least 300,000 miles of reliable engine life.
 
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 Originally Posted By: ted s
i own 6 cars with flat tappets
Use a CI-4 and don't worry about it.
 
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Added 3/4 of a bottle of ZDDplus to 5 qts in an 05 Accord 4 cyl. The tick at 1200 has done disappeared-hmmm-thought Zn/P was only for flat tappets eh?. Steve
 
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