Zinc phosphate in engine oil

[William M.]

Article in August 08 Corvette Enthusiast talks about the need for zinc phosphate (ZDTP/ZDDP) to minimize wear in older engines. Modern engine oil has eliminated this. The article recommends an engine oil supplement like Kirban Performance Products ZDDPlus.
I recently bought a 73 454 w/ original engine and 55K miles. I changed to Mobil 1 synthetic. Do I really need the supplement?

[Mark G.]

Re: Zinc phosphate in engine oil

The website I'm referring to is www.zddplus.com. I've asked the question about ZDDP and using this additive to some GM engineers and here are two replies I received.

Engine Oil Mythology


Bob Olree

Amazingly there are still a few people today, 60 years later, who believe that they need to use non-detergent oil in their older cars. Apparently it takes about 75 years for an oil myth to die.

Then there is the myth that new engines will not break-in on synthetic oils. Apparently there was an aircraft engine manufacturer who once put out a bulletin to this effect. Clearly the thousands and thousands of cars filled with Mobil 1 as factory-fill, which have broke-in quite well, should have put this one to rest. However this one is only 40 years old, so it has another 35 years to live.



Before debunking this myth we need to look at the history of ZDP usage in engine oil.



Zinc dithiophosphate was first added to engine oil to control copper/lead bearing corrosion. Starting in 1942, a Chevrolet Stovebolt engine with aftermarket copper/lead insert bearing connecting rods was the standard oil test . The insert bearings were weighed before and after test for weight loss due to corrosion. The phosphorus levels of oils that passed the test were in the 0.03% range.



Knowing that this higher level of ZDP was good for flat-tappet valve-train scuffing and wear, some oil companies dumped even more in thinking that they were offering the customer even more protection. However it was soon learned that while going above something like 0.14% phosphorus might decrease break-in scuffing, it increased longer term wear. At about 0.20% phosphorus the ZDP started attacking the grain boundaries in the iron, resulting in camshaft spalling.

Later in the 1970s, the ZDP level was pushed up to the 0.10% phosphorus range as it was a cheap and effective antioxidant, and increased antioxidancy was needed to protect the oil in Cadillacs pulling Airstream trailers from thickening to the point of not pumping. Recently, the need for this higher level of ZDP for protecting the oil from thickening has been greatly reduced with the introduction of more modern ashless antioxidants that contain no phosphorus.
















February 13, 2007

[Mark G.]

Re: Zinc phosphate in engine oil

This is the other reply from another GM engineer:


One additional comment: The website states, "[t]oday, ZDDP has been removed from practically all automotive engine oils." This is utterly false. The truth is that all API licensed ILSAC GF-4 engine oils have ZDDP in them (most are formulated to have about 0.08wt% phosphorus). The website is replete with similar false statements. I don't know whether the authors of this website are intentionally lying or if they are just terribly, terribly misinformed. Regardless, I wouldn't trust anything on this website and would not give this product any consideration.

[Duke W.]

Re: Zinc phosphate in engine oil

Article in August 08 Corvette Enthusiast talks about the need for zinc phosphate (ZDTP/ZDDP) to minimize wear in older engines. Modern engine oil has eliminated this. The article recommends an engine oil supplement like Kirban Performance Products ZDDPlus.
I recently bought a 73 454 w/ original engine and 55K miles. I changed to Mobil 1 synthetic. Do I really need the supplement?

SM oil is not the best to use in vintage Corvettes, and this includes Mobil 1. If you want facts, search this website for "CJ-4".

There will be an article on the subject in the next Corvette Restorer.

Duke

[Roger S.]

Re: Zinc phosphate in engine oil

Read:
http://www.digitalcorvettes.com/foru...ght=oil+zin c

I use the Shell Rotella 15W40 in my 1973 L-82.

Roger

[Jeremy D.]

Re: Zinc phosphate in engine oil

Ditto....I've used Shell Rotella 15W40 in all of my Corvettes and have had NO problems whatsoever...and that includes driving them like they were Fords at times.... And, the price is definitely right....we use it in all of our diesels at work!

[Duke W.]

Re: Zinc phosphate in engine oil

Brands are bunk! All you need to know is API CJ-4. There are scores of them.

Duke

[Randy G.]

Re: Zinc phosphate in engine oil

For many years I was on a Pennzoil product sponsorship with my racing team.

We started burning up pushrods, rod bearings and main bearings in mid 2004. Then, after blowing up 3 engines in 5 runs the Valvoline Racing Oils rep at the track was nice enough to come by my pit and talk to me. He told me he didn't want to sell me anything, but strongly recommended I contact my Pennzoil rep and ask if the GT Racing Oil I was getting from Pennzoil was the new "SJ" rated oil with reduced zinc and phosphates, which was required for selling their oil over the counter per the EPA.

My Pennzoil Rep never retuned my calls, and I gave away the last pallet full of oil I got from Pennzoil. At the advice of my fellow racers, I started purchasing Valvoline's Nitro 70 wt "off road use only" oil which retains the two additives. I have yet to have a lubrication related issue since I made the switch in 2005.

Valvoline's rep told me that in 2004 the World Of Outlaw sprint car racers were experiencing unbelievable rod bearing failures when the SJ rated oils were introduced to them. They run methanol alcohol in small block Chevy design engines. Whenever one of these engines would hit 10,000 RPM they would spin rod bearings and kick the rods out the side of the block. Valvoline reintroduced higher zinc/phosphate oils for off road use/racing applications only, and the problems went away.

Bob Olree's opinions and comments don't match reality. My checking account is proof.

Note the Valvoline sticker just in front of the rear tire.



RG

[Roger S.]

Re: Zinc phosphate in engine oil

Info from the Shell Answer Man about the wear additives in Rotella the old CI-4 verus the new CJ-4 spec's.
He, actually a she, said

...........................CI-4..............CJ-4
Zinc.................. 1390 ppm.......1210 ppm

Phospherous.........1265 ppm.......1110 ppm

About 12% lower for the new oil, but much more than the regular car SM spec oil.

Roger

[William M.]

Re: Zinc phosphate in engine oil

I hear what you guys are saying about the Shell 15W40. But I live in the Northeast and plan to exercise my car sparingly during the winter. That weight scares me.

[Paul H.]

Re: Zinc phosphate in engine oil

I hear what you guys are saying about the Shell 15W40. But I live in the Northeast and plan to exercise my car sparingly during the winter. That weight scares me.

I've been using the 15W40 Shell Rotella in all my old cars here in Mass and I exercise them in the winter as weather allows. No problems with that weight oil, especially with garaged cars.

[Jeremy D.]

Re: Zinc phosphate in engine oil

If we can get sorely-worn-out Detroit Diesels with weak batteries to get fired up with 15W40 in them when it's zero out (with a little dose of sniffy, of course), I don't think starting a small block Chevy should be too big of a problem. If it's a major concern...put in a block heater, I guess......

[Jim T.]

Re: Zinc phosphate in engine oil

William M. I have bought Shell Rotella 10W30 at my local WAL-MART, but last time I checked the same store did not have it on the shelf that day. I was in the local O'Reilly Auto Part store couple of weeks ago and they had the 10W30 Shell Rotella on the shelf.
Have to hunt for what you want sometimes. I found only one auto parts store that stocks the ZEREX G5 antifreeze.

[Duke W.]

Re: Zinc phosphate in engine oil

I hear what you guys are saying about the Shell 15W40. But I live in the Northeast and plan to exercise my car sparingly during the winter. That weight scares me.

15W-40 is okay for cold starts down to about 10-15 degrees F. This would be the temperature inside the garage, not outside.

CJ-4 is also available in SAE 5W-40, but may not be as commonly available as 15W-40; 5W-40 is okay for cold starts to about 20 below zero F.

Duke

[Stuart F.]

Re: Zinc phosphate in engine oil

I picked up a 3 gallon pack of Shell Rotella 15w-40 at Sam's club today for about $27.00 in prep for my next oil change on my 63 340 hp. I have a second mission to tackle on this oil change; I must remove the two bolts securing the pressure by-pass valve. I used to always remove the unit in order to change the o-ring filter housing gasket. After a while, one bolt head got rounded off and I'll be darn, but it's hard to get a hold of. You can't get a vice grip on it and even a metric socket won't work, just to get it out! I must have changed oil 4 or 5 times using the old gasket and putting off dealing with that bolt. Now I have new bolts and a new set of bolt extractor sockets to play with. That sucker is comin outa there!
I have had an adapter kit to go to a spin on filter now for the last 20 years, but have yet to do so. As long as the cartridges are still available I'll continue to use them. I believe the original filter can could withstand a 30 caliber bullet, but not the repros or those tinny spin ons.

Stu Fox