Zinc Additive for 6 Cylinder??

Marcus

Marcus

Well-known member
ALL: I always add a zinc additive to the oil in my Hi-Po 289 Mustangs (both of them, and the extra cost is well worth it in the long run!); however, recently purchased a '66 Mustang Convertible (for the wife, of course!), six cylinder and wondering if I should / need to use a zinc additive in the six? Anyone have any experience with this?
 
If the six is stock, no need for extra zinc! It is only needed for high pressure racing valve springs, when you're trying to turn 7-8,000 RPM or more.
 
40 Deluxe - Thanks for the response; not so much concerned about the high RPM aspect as I am about the flat tappet aspect. Never had one of these 6's apart, so that is the issue. I also add zinc additive to my flatheads, for that very reason.
 
I am confused..............I have been told that flat tappet engines should have the extra zinc. It has been recommended to me by a member of the Portland OR TBird Club to use Valvoline VR1 racing oil as it has the zinc that these engines needed. Thoughts?
 
personally I use zinc in my SBF with flat tappets. I'm not taking a chance of $15 every 3000 miles.
 
Marcus said:
40 Deluxe - Thanks for the response; not so much concerned about the high RPM aspect as I am about the flat tappet aspect. Never had one of these 6's apart, so that is the issue. I also add zinc additive to my flatheads, for that very reason.
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Oil did not have zinc in it when your flatheads were born so they don't need it now. Any modern oil is far better than any oil available in the '30's or '40's, even the '50's. This "old wives' tale" of needing extra zinc in any and all flat tappet engines is just another urban myth!
 
The zinc may or may not be a myth, but there are volumes on the old car sites to read about it. Personally, I'm running either 10w-30 or 15w-40 diesel oil in everything old I have for peace of mind.
 
If its flat tappets - use the oil with at least 1000 ppm of zinc (zddp) or greater.

Shell Rotella has this.

You can call the Shell hotline and give them the information from your container (be it bottle,jug or barrel) and they will give you the zddp count for that batch of material.

Oldmics
 
40 Deluxe said:
Oil did not have zinc in it when your flatheads were born so they don't need it now. Any modern oil is far better than any oil available in the '30's or '40's, even the '50's. This "old wives' tale" of needing extra zinc in any and all flat tappet engines is just another urban myth!
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I first thought so too, just another advertising gimmick to separate me from cash in my wallet.
I'm not an oil chemist and haven't been working on flat tappet/solid lifter engines for years & years, so I have to rely on information shared by recognized experts who do have access to chemical labs.
Here's some info from a fellow who is a well respected Technical Editor/Authenticity Chairman, and was building y-block engines for decades before I even knew they existed.

Zinc was in the older motor oils. It has been effectively removed because it contaminates catalytic converters & modern emission equipment.
"Zinc and Phosphorus (ZDDP) is an anti-wear component necessary in older engines. It has been reduced in most modern engine oils because of EPA standards and the reduced requirement for modern engines."
https://www.ctci.org/gilsgarage/EngineOil2.php

"It will only get worst because projected future oil spec revisions will likely reduce ZDDP content even more"
https://www.ctci.org/gilsgarage/EngineOil.php

Some folks may disagree about how necessary the previously included / removed ingredients are, but I'll be using diesel rated oil in my pre emission era engine. If for no other reason than it can't hurt, and it could help.
.
 
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dmsfrr said:
I first thought so too, just another advertising gimmick to separate me from cash in my wallet.
I'm not an oil chemist and haven't been working on flat tappet/solid lifter engines for years & years, so I have to rely on information shared by recognized experts who do have access to chemical labs.
Here's some info from a fellow who is a well respected Technical Editor/Authenticity Chairman, and was building y-block engines for decades before I even knew they existed.

Zinc was in the older motor oils. It has been effectively removed because it contaminates catalytic converters & modern emission equipment.
"Zinc and Phosphorus (ZDDP) is an anti-wear component necessary in older engines. It has been reduced in most modern engine oils because of EPA standards and the reduced requirement for modern engines."
https://www.ctci.org/gilsgarage/EngineOil2.php

"It will only get worst because projected future oil spec revisions will likely reduce ZDDP content even more"
https://www.ctci.org/gilsgarage/EngineOil.php

Some folks may disagree about how necessary the previously included / removed ingredients are, but I'll be using diesel rated oil in my pre emission era engine. If for no other reason than it can't hurt, and it could help.
.
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My comments were geared toward the perceived "need" for extra bottles of zinc to be poured into any and all flat tappet engines. Currently this is not necessary except with race springs.
As for what the future holds, that is all speculation. As far as using Diesel rated oil, new Diesels have roller lifters and catalytic converters, so what is their oil's zinc content??
 
40 Deluxe said:
As for what the future holds, that is all speculation. As far as using Diesel rated oil, new Diesels have roller lifters and catalytic converters, so what is their oil's zinc content??
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It's my understanding the chemical content in the newer diesel engine oils is changed as well. Those newer engines will require a different and properly rated oil.

My 2¢ worth... engines and the lubricating oils for them are a product of the time they are/were both created, and they are effectively designed to work with each other.
A newer engine with more modern parts and sophisticated emission equipment needs a compatible oil.
The opposite is also true. With the exception of non-detergent oil and other improvements, older engines 'need' an oil that is as similar as possible to what would have been used during that time. Zinc and phosphorus was in the back-in-the-day oil, and is still in the current/early crop of diesel rated oils.
It doesn't have to be a separate pour-in additive, but can be.

Maybe we just need to agree to disagree?
 
Thanks all for your input. DMSFRR...........we have chatted about this before and I value your input. As for me I will continue to use Valvoline VR1 for its zinc content in my 302. Yes it costs extra but at one oil change a year it is no big deal. All I really know is that this engine purrs like a kitten but can roar like a lion!!
Thanks everyone....................
 
Marcus said:
ALL: I always add a zinc additive to the oil in my Hi-Po 289 Mustangs (both of them, and the extra cost is well worth it in the long run!); however, recently purchased a '66 Mustang Convertible (for the wife, of course!), six cylinder and wondering if I should / need to use a zinc additive in the six? Anyone have any experience with this?
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Are you planning on keeping the 6cyl, or replacing it with something more entertaining?
If you're keeping the Mustang as an original / collector type car, for the long term...
I'd say go for the zinc. (if you hadn't already guessed)
 
dmsfrr - I had planned to simply flip the '66 after some minor work - but the wife REALLY likes the idea of the six, and it is a convertible with C4 and A/C, so I'll probably be keeping this one for her. I have several other Mustangs, and they are all too powerful for her; plus I have an additional Hi-Po 289 that I was considering dropping into yet another hotrod project that I was working on - but a friend saw that project and just had to have it...........and another friend begged me to part with the stored 289 (see previous post about storage requirements), and I am now (nearly) project free. I usually run Valvoline VR1 in all my (14) antiques, but was really curious about the need because of the six cylinder. VR1 may be overkill, but cheap insurance! Thanks for your input.
 
wbedwards said:
The zinc may or may not be a myth, but there are volumes on the old car sites to read about it. Personally, I'm running either 10w-30 or 15w-40 diesel oil in everything old I have for peace of mind.
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It's my understanding that not all diesel rated oils have it. I was using Rotella in everything but then read they reformulated and took out the zinc. The Motorcraft powerstroke oil does have the zinc and is about $20 for 5 quart jug at Mal-Wart. I'm now using it (and a little Lucas) in my old engines.
 
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dmsfrr said:
Some folks may disagree about how necessary the previously included / removed ingredients are, but I'll be using diesel rated oil in my pre emission era engine. If for no other reason than it can't hurt, and it could help.
.
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And I'll second that, dmsfrr.
I did a comparison a few years ago and found that Shell Rotella 15W-40 diesel oil had a LOWER amount of zinc than at least two other readily available brands and was surprised (I had been using it for many years). So I switched to Valvoline Premium Blue diesel oil and it is popular at many chain auto parts stores around here.
AND, we need to keep lookin at these values and warn each other if one of the companies reduces or eliminates their zinc content.
 
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