Zinc in oils

6

69ranger

Well-known member
Good morning everyone,
I dont want to open up a can of worms here, on oils, or what brand is the best, and such, but I wanted to discuss zink additives and how it effects old engines.

The subject of Zinc in oils came up the other day, with one of my friends. This discussion centered around small engines, and engines with the older flat tappet designs.
I have been using Diesel oils, in my small air cooled engines for the last 3 or so years, but as these additives continue to me phased out, what then?

I started using Phillips Trop-Artic in my vehicles years ago, because it was a good oil at a decent price point.
I have ran this oil in many engines, over the years and never had any issues, with it. Engines are clean on the inside, and have lasted very well.

So, I am still running Phillips Shield, that I get at the farm store in the cars, and my Cubs, and the other I-H tractors that I own.

What do you all think? Should a zinc additive be added to these old engines? Maybe run diesel oils, that are higher in Zinc?
How long before all Zinc is gone from oils?

What oils do you all run, and what are your thoughts?

Brad
 
yes this can be a can of worms, for the most part Zinc is already gone from most oils, yes its good to have in old engines, it is like many things we use to have, it worked good but someone decided its bad for us and took it away
 
Zinc provides a "cushion" on the cam lobes. This is mostly helpful for flat tappet (non roller) lifters like cubs have. The cushion comes into play at higher RPM's when the valves are being slung open and the valve spring load is slamming them back closed on the back side of the lobe.
The valve springs are often not strong enough to keep a zero air gap on the cam lobe at higher RPM's. That's where 1800 - 2500 RPM's come into play.

These low RPM engines never turn fast enough to create an air gap between the cam and the lifter so there is no real need for the zinc cushion. I run regular motor oil without any zinc. If you like the idea of some cushion, spend the $8 for a bottle of zinc additive.

I've seen more engines destroyed from no oil pressure than those retired due to cam lobe wear on the back side of a cam lobe.
Has anybody replaced a C-60 Engine Cam due to wear?
 
Camshaft profile and valve spring load plays a big part as well. Old tractor engines, in general, have very gentle cam profiles and pretty soft springs. I don’t think I’ve seen any old tractors wipe cam lobes.
 
This probably true. Its zinc deal may be about like the lead in fuels, and not a real issue, except under extreme conditions.

The small engine guy here in town, swears its a problem with air cooled engines. He was the one that told be to run Rotella in my new, at the time Zero turn mower..

While I have seen both sunk valve seats and wiped out cams and lifters, in V-8's, that I have worked on, never a tractor engine.
Mostly Chevy engines from the late 80's and a few fords, and one twin cylinder Briggs engine.

Several car and truck engines that I rebuilt in the late 80's and early 90's that are still running strong.
I have an old truck with a 390 and a pretty hot cam, and heavy valve springs, that has towed hard, until my diesel truck came along, and so far so good.
Several small blocks running around in some of my other old stuff, that have not suffered.
 
The easiest and cheapest way to get an easy to get zinc oil is to run diesel oil, Rotella still has pretty good amount. It has more than dello or castrol diesel if I remember the last year results I saw. It has about the same about as the gas 10-30 of years ago before they started reducing the zinc. And yes you can run "diesel" oil in gas. It actually has the API spark ignition approved symbol on it if you don't believe me look. Any APai certification with and S is for spark ignition any that starts with a C is compression ignition, ie diesel.
 
outdoors4evr":3hhyrrs7 said:
Zinc provides a "cushion" on the cam lobes. This is mostly helpful for flat tappet (non roller) lifters like cubs have. The cushion comes into play at higher RPM's when the valves are being slung open and the valve spring load is slamming them back closed on the back side of the lobe.
The valve springs are often not strong enough to keep a zero air gap on the cam lobe at higher RPM's. That's where 1800 - 2500 RPM's come into play.

These low RPM engines never turn fast enough to create an air gap between the cam and the lifter so there is no real need for the zinc cushion. I run regular motor oil without any zinc. If you like the idea of some cushion, spend the $8 for a bottle of zinc additive.

I've seen more engines destroyed from no oil pressure than those retired due to cam lobe wear on the back side of a cam lobe.
Has anybody replaced a C-60 Engine Cam due to wear?
Click to expand...
If I remember right from the last additive bottle I read you don't need to add the whole thing it's a partial amount. And even regular oil has zinc in it...it's just 1/3-1/2 the rate of the diesel oils and way less than the break in or race oils have.
 
69ranger":204h8b8w said:
This probably true. Its zinc deal may be about like the lead in fuels, and not a real issue, except under extreme conditions.

The small engine guy here in town, swears its a problem with air cooled engines. He was the one that told be to run Rotella in my new, at the time Zero turn mower..

While I have seen both sunk valve seats and wiped out cams and lifters, in V-8's, that I have worked on, never a tractor engine.
Mostly Chevy engines from the late 80's and a few fords, and one twin cylinder Briggs engine.

Several car and truck engines that I rebuilt in the late 80's and early 90's that are still running strong.
I have an old truck with a 390 and a pretty hot cam, and heavy valve springs, that has towed hard, until my diesel truck came along, and so far so good.
Several small blocks running around in some of my other old stuff, that have not suffered.
Click to expand...
I have read and heard from people that know more than me that it usually bis a non issue even on the older stuff that's worn and broken in. So the small blocks you built in the 90s and 90s had 10-20+ years of use with oils with zinc in similar amounts that today's diesel oils have before they reduced the levels. And I have repeatedly read these engines will be fine on modern oils. But if you rebuilt or swap cams you need to run a high zinc oil at first to lessen the chance of wiping a cam or lifter
 
The reason zinc was lowered is because it eventually clogs converters. Not all diesel oils have quantities that are needed for flat tappet engines either. You have to go on to the oil's web site and check the msds to see whats in it. Oils for flat tappet cams have 1200+ ppm of zinc. Spring pressures are so low here on these that until recently I never bothered but lately since I've been working it hard cutting grass and it's getting tired I have been using better stuff- and it's only 3 quarts
 
Clemsonfor":252kosmq said:
The easiest and cheapest way to get an easy to get zinc oil is to run diesel oil, Rotella still has pretty good amount. It has more than dello or castrol diesel if I remember the last year results I saw. It has about the same about as the gas 10-30 of years ago before they started reducing the zinc. And yes you can run "diesel" oil in gas. It actually has the API spark ignition approved symbol on it if you don't believe me look. Any APai certification with and S is for spark ignition any that starts with a C is compression ignition, ie diesel.
Click to expand...

Yep. A good quality diesel oil would be what I used if I was worried about zinc.

I used to run JD oil in my Cub for a while!

Al
 
Clemsonfor":1sa5s4du said:
I have read and heard from people that know more than me that it usually bis a non issue even on the older stuff that's worn and broken in. So the small blocks you built in the 90s and 90s had 10-20+ years of use with oils with zinc in similar amounts that today's diesel oils have before they reduced the levels. And I have repeatedly read these engines will be fine on modern oils. But if you rebuilt or swap cams you need to run a high zinc oil at first to lessen the chance of wiping a cam or lifter
Click to expand...
I largely agree with these comments. A Cub engine should get along fine with about any spark or Diesel rated oil. Even the low-grade non-detergent 30 weight oils are probably okay although I wouldn't use them. (Most of these were labeled "ND" but are now labeled "general purpose" or "compressor" and say "not suitable for use in engines".) For every person worried about not enough ZDDP, there is somebody else that wants to avoid detergent oils. They end up with the "general purpose" oils that don't have any additives (and even they haven't been reporting cam wear).

I don't like the practice of adding anything out of a magic bottle to the engine oil. I only make exceptions to this for VERY SPECIFIC reasons. They are:
- break in after an engine rebuild (pointless if you didn't install a new/reground camshaft and tappets),
- suspected case of stuck rings and a shot of overhaul in a can is worth a try before tearing it down.
The break in situation is almost certainly better handled by using an oil that is formulated for break in than by adding something to the oil. Another option is to use motor assembly oil/grease during assembly. In any case, I wouldn't leave the treated oil in for an extended period. Dump the break-in treatment at the earliest recommended time. Change the stuck ring treatment as soon as it has a reasonable chance to work.

The reasons I don't like using additives is that the collection of additives in any specific oil is blended to work as a package. It is balanced. Dumping some other additive in will disturb the balance. For example, adding ZDDP increases the acidity. Simply adding ZDDP may add protection to the camshaft at the expense of increased corrosion of all the plain bearings. For a lightly used engine, acid from moisture that doesn't get cooked out is a bigger problem than anything specific to the camshaft.

If you are really concerned about ZDDP levels, do as Gary S. suggested and find an oil that has the amount you think is needed.

Here is a link to more details:
https://www.onallcylinders.com/2018...e-with-off-the-shelf-motor-oil-to-save-money/
 
Thank you all for the info. Lots of well thought out info, and I am trying to read more and learn more about this.

Sounds like I should me more worried with my old ford v8 engines than these old low rpm tractor engines.
 
I'm in the tail end of some much needed maintenance on my 184's C-60. To the best of my knowledge, the only oil that motor has seen is IH-Low Ash. Whatever formula they have in that is great. For a 50+ year old motor, there's little wear in it. Bores are still in spec, granted on the high side of tolerance. Pulled the head off for the first time since at least 2006 and the carbon build up was near negligible, but that's probably straying away from the topic of zinc...
 
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