Hi All-
I've been reading about this... anybody use zinc additive?

Yes, but not all oils, additive packages or zinc that you can add separately are created equal. Everyone and their brother (including me) will have an opinion. In my opinion your best bet is to arm yourself with engineering articles that are not trying to sell you anything. Here is a long read that starts in 2013 and ends with testing in 2022. it should get you started. https://540ratblog.wordpress.com/2013/06/20/motor-oil-wear-test-ranking/

And here is an abbreviated explanation of Zinc quantities in oil, go to post #14 https://www.stevesnovasite.com/threads/zinc-in-oil.642986/

Here is one man's opinion: You need to have zinc for flat tappet cams. They took out the zinc compounds that they used forever out of oils because it damages catalytic converters and all new cars have roller cams and don't need it anyway. Use regular brand name oil and add a zinc additive product. Regular passenger car oils have detergents and other additives which is good. Add the missing zinc and you are good to go. Diesel engine oils have too much detergent. Racing oils don't have enough detergent. This is the information I have gathered from much reading on the subject over the years.

BB: from the link... an enlightening quote...

"Whatever you do, DO NOT add aftermarket zinc additives to low zinc oils. Because I did testing on this exact situation and found that adding zinc to low zinc oils, ruins an oil’s chemical properties and SIGNIFICANTLY reduces its wear protection capability. The Oil Companies always say to “never add anything” to their oil. Believe them, because they know what they are talking about. After all, they are the experts on their own products."

So sounds like look for the oil that has zinc and phosphorus already mixed in, and at levels that a 400HO was used to in March of '68 (to Bob S's point)... not sure how to accomplish that!

Great info, THX!

I've been adding ZDDPlus to my '68 at every oil change since the ZDDP content in oil was being reduced.

Jim-- Dunno...This guy is truly reputable... and he really doesn't like messing with the chemistry !

And one of the very worst aftermarket additives I have ever tested is “ZDDPlus” zinc additive, which claims to greatly improve a motor oil’s wear protection capability. But, when put to the test, it actually destroyed the wear protection capability in “every one” of the several different motor oils I tested it in, making the oils far WORSE than they were to begin with. You can see the numbers in my Wear Protection Ranking List for yourself. My Scientific Engineering Torture Test on motor oil proved over and over again, how BAD that product really is. So, you CANNOT believe any aftermarket motor oil additive advertising either. Buyer Beware!!

His insights and test and conclusions on filters is also striking... I'm rethinking my whole lube strategy!
( Wow BarnBird...GREAT Article)

Hmmmmm

I really hate getting involved in these types of conversations because People understandably get very territorial and the last thing, I want to do is offend anyone. I used to espouse my beliefs one of which to add zinc to your choice of motor oil, but I have changed that opinion based on not only this but many other engineering articles over the last few years. Zinc is an important part of an additive package but only one of many other just as as important anti wear factors. As a former mechanic I felt kind of stupid for never even considering that by adding a compound to a base oil with an already extensive balanced additive package I could actually be degrading it by chemical processes that can occur under load. My father was an old school mechanic and he taught me from a very young age that you did not need to add anything to motor oil if you were using the right quality oil, I guess I thought I knew better. I am no engineer but one thing I do know is to never trust any manufactures claims of how good their product is because if I did everybody's product would be the best there is.

So the moral of the story is to buy specialty classic car oil designed with zinc additive?

Right now I'm concerned with the oil, itself. Having standardize on conventional Pennzoil for all my vehicles decades ago, I am having a harder and harder time finding the straight 30W recommended for the 400HO engine. I just checked Walmart online and the Pennzoil HD30 I've used for years is $22.18 a quart.

I skimmed through the document and saw the same warning about ZDDP additive, oh crap. I too have been using the stuff for years. I am thinking of shifting to VR1 10W-30 because of that note. It has high zinc, it is conventional and seemed to do pretty well overall,

I run flat tappet cams in all my engines and use VR1.
But.........I have been working on these cars for years and years and personally have never seen a worn out flat tappet cam or lifters except on the Chevy 305's that all had bad heat treatment or metallurgy on their cams.
I also have ran cheap Walmart oil without any additives on flat tappet engines for past 20 years without any problems.

X2 VR1. Used it for years with flat tappet cams
Good stuff.

All great observations and comments-- what super bunch of 'Birdbrains!

This engineer is one of those invaluable people that take significant time out of their lives to study a topic so seemingly mundane and so incredibly important; FROM AN INDUSTRY full of misinformation and assumption to come to incredibly DETAILED TRUTHS just for the purpose of sharing with total strangers eager to know. Kudos.

... and BarnBird to have the article handy..kudos to you as well.

Driven makes a line of motor oils specifically designed for Hot Rod Engines that contain additives specifically for Hot Rod type engines, including extra rust preventative for long term storage, the shop that rebuilt my 400 put me onto. Seems like an answer for all of us, not racing oil, not modern engine oil with a bunch of ZDDP added, an oil designed specifically for our type of cars in todays world.???????????