The Stovebolt Site Forums The Shop Area Engine Shop zink phosphorus

As I understand it, the oil companies have removed zink in their
oils. This puts flat tappet engines in danger of flat cams and damaged lifters. GM did market a product named E.O.S. or engine
oil supplement that replaced this zink for newly rebuilt flat
tappet engines. Does anyone know of another product that might
work in place of this. I have been told that you can use oils designed for diesels but zink is also being eliminated in these
oils.

I just found out the same concern. As I understand if one is to buy the engine oil that today is used for the disel engines of today will work in place of the older oil. I have a friend who has an older restore with cam and lifter damage. He is a seasoned experienced mechanic & told me this onfo. and I believe he knows what will work. I am going to change as soon as possible.

I think doing a 'search' on this topic will give you several days of reading!

E.O.S. has been around for 50years that I know of. I sold it when I was a parts man back in the 50's and 60's. I haven't been in a Chevy dealership in decades so I don't know if they still carry it. Basicly it was just an oil thickener like STP.
And as Jeff mentioned this subject has been beat to death, not to worry unless your talking about a high performance engine.
Denny G

Look into the Valvoline V1 series oils. They are used by the race car guys. It has the higher levels of zinc in it. I like and use it. I also think that STP is good, too.

Go figure.

EOS has been discontinued, besides, GM actually stated that it should not be used as a regular oil suppliment as it can cause pre-ignition problems. It was only intended as a break in lube. There is a similar product from Crane Cams, however, same deal, only used for braek in. According to the guys at the machine shop I use (the original owner has over 50 years experience with engines) they say that proper break in is the key, once the engine is properly broken in, there should be no issues with running regular oil. However, if you are concerned, this might be another soultion.
BTW, I've heard all of the horror stories in which the so called "professional engine builder" that assembled the engine quickly blames the oil for whatever failure occured. Sounds like a dodge to get out of warranteeing sloppy work to me.

I wonder if Wynn's Friction Proofing still on the market.

Yup.

how about www.zddplus.com ?

I know a lot of guys who are using Shell Products Rotella - T in 30 Wt. to break in their race engines as it has all the Phosphorus, Zink and Sulphers that the old oils used. That is what I am going to use to break in my Chevy with. Kendall still makes the oil with the old ingredience in it I believe but expensive. Rotella -T can be brought at Walley World fairly cheap.
62Blue

I saw a couple of ads in a car magazine for outfits that are selling "classic car oil" with zinc in it. The local farm store had a sale of house brand oil with the API L rating so I bought several gallons. It's the M rated oil that's short on zinc.

GM makes EOS again. new part # 88862586

Indeed we have seen a lot of info on the reduction of ZDDP in motor oils online for the last couple of years.
The bulk of which unfortunately are myths and parrotted misinformation accompanied by anecdotal evidence, if any at all.

I always do my own research and thinking regardless and what follows are my personal conclusions to date.

To figure out what amount of zinc/phosphorus (ZDDP) is safe for my 235 and 261, I first was curious about the history of concentration levels.

During the 40s phosphorus levels were around .03%
In the mid 50s, when more aggressive cam grinds and higher valve spring pressures became more common, phosphorus levels were increased to around .08%
Test showed that although scuffing is reduced during initial break-in, too much zinc/phosphorus is not a good thing for the long term.
At 0.14% wear is increased over the long term and at 0.20% the ZDDP starts to attack the iron in the cam.
By the 70s heavy duty oils had about 0.12-0.16% - Cams had very high lift and spring pressures were extreme.
Levels have been reduced in the last 10-15 years to protect exhaust catalysts.
Today typical gasoline motor oil has a maximum of .08%
Same as oil during the 1950s...

Diesel oils, like Rotella used to have about 0.11% phosphorus, which has been reduced in 2007 to the current .09% in 15W-40 multi-grade.
Straight-grade like SAE30 remains unchanged and is still in production.

The people who promote/push the ZDDPlus additive advise against the use of diesel oils in gasoline engines, to no surprise.
After mixing their additive with current standard motor oil as recommended, the resulting level of phosphorus is 0.19% !
That is about twice the concentration compared to what has worked fine for 50 years...
I'm rather skeptical that their product will help my engines.


There are hours of reading info on all this online from various sources.
The historical data I provided is derived from the GM Powertrain Fuels and Lubricants Group.
The levels on Rotella oils are derived from independent oil analysis data.
The ZDDPlus info is available on their site.

On my 30+ year old 235, I use Rotella SAE30 all year round.
My fresh 261 gets the same oil in summer and Rotella 15W-40 during the colder months, with around 30 degrees as the coldest cranking temperatures.

I believe there is plenty of ZDDP in current Rotella oil.
The extra detergent and dispersant additives may not be ideal for high performance engines, but work well for our motors, especially when older with more blow-by.
To be sure, I will have my oils analyzed before the next oil changes and will update this post if needed.

When you have your motor oil analyzed by a lab, unless there are catastrophic amounts of metals in it, a single analysis does you no good. It takes a series of samples to track chemical and metal levels to be effective...they are looking for a trend that would indicate abnormal wear or values consistent with normal wear.

One test does you no good. That's how our lab explained it.

Stuart

Your lab is right, Stuart. To obtain useful information about engine wear, several tests over time are more helpful than a one-time snapshot.
However only one test is all that's needed to measure the ZDDP and acid levels of the oil in use, which is what I'm interested in.
I'm also curious about the diminishing effectiveness of additives over time and how long I can go between oil changes.
If the first test gives good results, I keep using the oil and do another test after a reduced interval from the previous.

Chris

Here's a tech service bulletin to supplement what Chris explained.
https://www.amsoil.com/dealer/techservicesbulletin/MotorOil/TSB%20MO-2007-08-08%20Flat%20Tappet.pdf

There are very few products available with the levels of zinc and phosphorus that you are looking for. The old timers are right about diesel oil, but today's CJ-4 rated diesel oil is not acceptable for your application. The exhaust after-treatment systems cannot function properly with those minerals. You need a CI-4 or earlier type oil, rated for the older diesels. You can probably find some bottle stock out there, but pay attention to the label. Don G is right about the Rotella-T. It's the only oil on the market with acceptable levels because (for now) it is most commonly used in tractors. There are no good additives available unless you get into the racing stuff, and that just doesn't pay off.