ZDDP Content

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Dec 8, 2019
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Location
Virginia
I have a Ford Model A with a 90 year old re-manufactured engine that has a low pressure oil system, flat tappets, and babbitt bearings. I want to add Zinc and Phosphorus.
I'm looking at three possibilities - ZDDPplus (about $10) , Riselone 3X Engine Oil Supplement (about $5), or STP Engine Oil Treatment(about $3). All three claim to contain ZDDP.

Where can I find out how much each contains and how much do I want in a five quart crankcase?
 
You valve spring pressure is so low (unless you hot rodded it) that you can run anything. A bigger concern is you have no oil filter. You do not want detergents, because you need to particulates to fall out of suspension into a nice sludge layer on the oil pan. In addition, some additives might attack Babbitt I think you want non-detergent mono-grade oil.

Rod.
 
I'm using Rotella T4 15w40. The thinking among the Model A group is that modern oils are much better than those back in the day but, the removal of Zinc required for modern catalytic converters and the EPA is detrimental for old technology engines. I'm just trying to figure out if the $3 or $5 stuff that I can get at Walmart is sufficient, or if I need to buy the $10 stuff and pay to have it shipped.
 
Briggs and Stratton lawn mower oil would be a good choice as close the same technology as possible.

Rod
 
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I hadn't heard about the additives attacking Babbitt. It seems to not be as durable as modern insert bearings. I do have an oil filter that is a modern add-on, not available in 1929.
 
My understanding is Rislone 3X has:
15600 ppm Zinc
13400 ppm Phosphorus

I think this information might have come directly from a product data sheet, so look around and you might be able to confirm.
At the time I was looking this seemed to be the best option, but i don't have any info on the STP product.
Use this in a dilution calculation to get what you want.
 
Originally Posted by ragtoplvr
Briggs and Stratton lawn mower oil would be a good choice as close the same technology as possible.

Rod

The Briggs is a race engine in comparison.
 
My uncle has ran SAE 40 oil with Rislone ZDDP additive in his model A for years. I know the engine has not been opened since at least the 1970's. Just add the entire 11oz bottle.
 
Originally Posted by PowerSurge
My uncle has ran SAE 40 oil with Rislone ZDDP additive in his model A for years. I know the engine has not been opened since at least the 1970's. Just add the entire 11oz bottle.

Which pretty much goes to show that no matter what you put in it, it will run. There's absolutely no reason for increased ZDDP in that engine, at least above what a normal oil would have. A good xW-40 oil would run just as well such as Mobil 1 0W-40. Or if you prefer maybe Delo 5W-40.
 
They have not removed those addatives. They only lowered the amount in the oil. Still plenty for my jeep with flat tappits and all those 5.7 chevies running around. When the car was made did they even have addatives in the oil? Or did they just use a sae 20 or 30 mineral oil?
 
Originally Posted by kschachn
Originally Posted by PowerSurge
My uncle has ran SAE 40 oil with Rislone ZDDP additive in his model A for years. I know the engine has not been opened since at least the 1970's. Just add the entire 11oz bottle.

Which pretty much goes to show that no matter what you put in it, it will run. There's absolutely no reason for increased ZDDP in that engine, at least above what a normal oil would have. A good xW-40 oil would run just as well such as Mobil 1 0W-40. Or if you prefer maybe Delo 5W-40.

Would a synthetic be ok for rope or leather seals?
 
Originally Posted by Chris142
Would a synthetic be ok for rope or leather seals?

It's interesting how people on hand decry that today's synthetics are just "highly refined" dino oils but then worry that they are going to damage something because they are synthetic.

A Group III base stock is chemically the same as a non-synthetic oil, right? It that worries someone then pick one with no Group IV or V composition.
 
Originally Posted by kschachn
Originally Posted by PowerSurge
My uncle has ran SAE 40 oil with Rislone ZDDP additive in his model A for years. I know the engine has not been opened since at least the 1970's. Just add the entire 11oz bottle.

Which pretty much goes to show that no matter what you put in it, it will run. There's absolutely no reason for increased ZDDP in that engine, at least above what a normal oil would have. A good xW-40 oil would run just as well such as Mobil 1 0W-40. Or if you prefer maybe Delo 5W-40.


"Absolutely no reason"? You really should talk to people that have been preserving these vehicles for decades for future generations to enjoy. Many antique car collectors do not want modern oils with their additives/dispersants/detergents in their engines. If you can produce Blackstone lab reports (or others) from these ancient engines to show less wear with modern oils, I am 100 percent open to passing that information on.
 
I found some info in the Consumer Product Information Database. For products containing ZDDP it lists Rislone 3X as having a 50% concentration and STP Engine Oil Treatment as having <5%. So, Rislone would have at least 10 times more than STP. Rislone also has a nice data sheet on their site that states that the Zinc and Phosphorus in a five quart crankcase would have a 1500 to 1800 ppm. Next oil change I'll use the Rislone.
 
STP Oil Treatment contains less ZDDP than modern API SN/SN+ oils so it will actually dilute the content, not add to it.

Also keep in mind that you can add too much ZDDP and actually increase wear due to toxicity. Another side effect of ZDDP is that it increases the coefficient of friction the higher the concentration. I like to see the least amount of ZDDP that'll get the job done for a particular application.

I also recommend using an oil that already contains the additive package that you need instead of using an aftermarket supplement with an unknown type of ZDDP. Additive clash from opposing chemistry can be a problem, especially with anti-foaming additives.
 
Originally Posted by PowerSurge
"Absolutely no reason"? You really should talk to people that have been preserving these vehicles for decades for future generations to enjoy. Many antique car collectors do not want modern oils with their additives/dispersants/detergents in their engines. If you can produce Blackstone lab reports (or others) from these ancient engines to show less wear with modern oils, I am 100 percent open to passing that information on.

Yes, absolutely no reason. There is no reason this engine needs highly elevated zinc levels.

Oh, and Blackstone Labs UOA would show nothing about comparative wear and would be useless for that information.
 
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