Zinc talk

I keep reading the posts about motor oil and zinc, so did some reading.

Here is my take.

Zinc and Phosphorus (ZDDP) was not present in motor oil before 1942.

ZDDP contributes to ash in combustion chambers, valve trains and emission controls, so you can have too much.

ZDDP was reduced lately to reduce the coating affects in catalytic converters.

The oil I use (Delvac) contains 1012 PPM of ZDDP, it looks like break in oil contains up to 2200 PPM, so quite a bit more. It looks like the jury is out on how much zinc is needed for a tappet engine. The heavier the valve springs and steeper the rise on the cam creates more stress on the cam/tappet surface. It also looks like the issue is not when the engine is running, but mostly during startup where the zinc is left after the oil runs away.

Based on this information, I am "believing" the oil is safe for me to use in my antique equipment, because of lower spring pressure and cam rise.

Opinions welcome.

I do oil analysis on everything every couple years and I haven?t seen even one ppm increase In wear metals on anything running the same amount of hours / miles

You agreeing that modern oils are safe, and no "special" oils needed?

There is such a thing as too much ZDDP. ZDDP is surface aggressive, and too much can be a detriment. ZDDP fights for the surface, blocking other additive performance. Acids generated due to excessive ZDDP contact will ?tie-up? detergents thus encouraging corrosive wear. ZDDP effectiveness plateaus, more does NOT translate into more protection. Only so much is utilized. We don?t need to saturate our oil with ZDDP.

From search.

That?s been what I see just by the samples

My guess is you are correct on the assumption it's safe in your old engines. Every cam I have heard of failing was in a "built" engine. Higher lift and stronger springs.

To me it stands to reason that the zinc will lessen the wear on any cam but without the high lift and stout springs wear will be minimal even without it.

At least on the old engines you can tell before it's a problem. When the light valve tic goes away you have cam wear or valve wear.

David
I looked into the oil GM recommends I use in my 2018 xt5. It's full synthetic.

I read you shouldn't put additives in oil that could damage O2 sensors and converters.

Don't see why you couldn't use anything in antique tractors.

I use 5w20 full synthetic in generators. 5w30 full synthetic in Jubilee. Rebuilt engine when I bought it. 5w30 straight oil in hydraulics and older tractors. I use what GM recommends in older cars and truck.
Don't see a need for any 10w30, 10w40 or 15w40 in my engines.

Zink
Why we need zink

It's been a few years since I last called the Shell Answer Man hotline, the 800 phone number. Rotella 15W-40 straight oil, not synthetic blend, was 1200 parts per million ZDDP, Your Delvac at 1012? PPM is in the same range, should be fine to use in old ag equipment without today's common roller rocker arms and valve lifters.

I've used Rotella in my 1950's vintage Farmalls and Air cooled Kohlers in Cub Cadets since 1996 when I got my brand new F-250 diesel, that strangely enough, doesn't need that much ZDDP because it has roller rockers and cam followers.

I had a brand new Mustang GT that I drove 700 miles to a NASCAR race in 1988, car wasn't completely broke in, burned a little oil, I used 10W-40 Valvoline in it, I stopped at 40-50 gas stations and truck stops Sunday night on the way home looking for a quart of Valvoline, not a quart for sale anywhere, but could have bought a semi-truck load of Pennzoil. When I got home at 3AM I put two quarts of Valvoline in the car. Since that night in 1988 I use the oil brand that's good and most readily available. Even most grocery stores sell quarts of Rotella! If Delvac was that easy to find I would use it in a heartbeat. I use Mobil 1 synthetic in my cars and pickups.

I do a lot of major engine over/hauls here, last year there were 13 of them,,a few years back (7or8) I did not use any kind of break in oil,,but at about that time I O/H'ed a 4250 and it used a good bit of oil for a few weeks,,we added a Zinc additive and it stopped using oil right away. Ever since that I have been adding Zinc with every O/H and the rings seem to seat right away. So I don't know the molecular composition of it,,I just know it works..

That's good to hear about the Delvac, that's what I use in my tractors, it's so reasonable with the rebate.

Yes, I agree with your summary. I have read a bit on the subject and talked to people in the engine building business. The Zinc is most needed in flat tappet (non-roller) engines with aggressive cam profiles. These engines must also use stiff valve springs to keep the valve train in contact with the cam at higher RPMs. Old tractor engines do not use aggressive cam profiles or heavy valve springs. Many new cars use roller followers making the lower zinc levels a non-problem.

One additional point: I have seen the zinc additive sold in small bottles to add to your oil...just add this to get the zinc level back to the good old days. It my understanding the zinc needs to be blended at the correct temperature and sequence with the other additives. It can not be just poured in and be effective.

I believe the Deere break in oil has 2200 PPM, so it is a high zinc oil, thus would recommend it for first run.

On one of the hot rod shows they had an engine rebuilt by a machine shop. They poured Oreillys Motor oil in it.(nothing wrong with that oil)They wiped the cam before the engine started. The builder rebuilt it, and brought them a case of zinc break in oil.

My 2011 LS Silverado 1500, 4.8L V8, conventional push rod engine, has rollers. I thought it was because it has 6k as the redline on the tach and develops its max hp at 5500 rpm, but now I see that maybe it's for 2 reasons.....and remembering the old GM problems with soft cams........

"old engines" ??? If your engine has "poured babbit" bearings, do NOT use a modern oil as the detergents will remove the bearing material. If your engine is newer than that, a modern "hd" type oil or a modern HP type oil both will work fine as they are nearly identical.

More important is.... are you doing snow removal or very very cold weather work, then you need to move the a 5w-xx oil. Since I dont plow below 32 degrees, a 15w-xx will work very very well.
if you can crank it over and it spins fast enough to start, you oil is not a problem....

Interesting that you car starts all year long, so what are you running in it???????