Author Topic: ZDDP in motor oil  (Read 2244 times)

Roy Schroeder

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ZDDP in motor oil
« on: April 17, 2010, 08:59:33 AM »
What are you guys using in your older cars now that the oil is being changed to eliminate the ZDDP in motor oils.
 I understand without this zinc the lifters can wreck the cam lobes.

Offline Otto Skorzeny

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  • 1956 Coupe de Ville aka Bismarck
Re: ZDDP in motor oil
« Reply #1 on: April 17, 2010, 09:13:26 AM »
ZDDP has not been eliminated, just reduced. There are still some oils that have the old levels of ZDDP.

I copied the following post from another Cadillac board. I think he has some good information - you be the judge.

Up until the 60's when they started hot-rodding the engines with higher valve spring pressures the ZDDP level was about 800 ppm.  Just as it is now.  Once they REALLY started hot-rodding them in the late 60's and into the seventies they had to add more ZDDP up to around 1600ppm because of spring pressures.

Mobil 1 15-50 is the best off the shelf synthetic since it has "about" 1200 ppm of ZDDP.  It works great all the way down to about 20 or 30 degrees.  I used it for ten years until I moved where it got colder than that.  You will also never find sludge in a Mobil 1 engine.  The new 5-40 TDT has 1000 ppm of ZDDP which is enough for a stock caddy engine considering the very low spring pressures.  It's got an incredible add pack.

Due to my very short trips in 0 to 10 degree weather over the last year I figured that since I had to change the oil so often even with Mobil 1 I may as well go dino which lead me to Valvoline VR-1.  They make one for racing without the detergents needed for the street and another for the street with the detergents.  VR-1 has about 1400 ppm of ZDDP and they make it in 10-30 as well as 20-50 and single weights.  It covers all the bases for an old V-8 and it's available off the shelf.  At least at the NAPA's where I live.

Considering the very low spring pressures on a stock Caddy motor I think 800 ppm would be just fine but I really don't trust that number since the ZDDP dissipates over time unless you have to add and oil analysis has shown that some of these newer oils don't have the ZDDP levels they SAY they have.  Some have been found to only have 600 ppm.  The biggest thing to watch out for is the starburst on the container and the lighter weights.  Those are the ones with lowered ZDDP and for God sakes, anything with a green label on it needs to be avoided like the plague in a vintage motor.

Adding something like ZDDP Plus is a good idea but I quit doing that because it changes the chemistry and the add-pack of the oil and that could cause problems.  I think the chemists know more than I do.  Then there is the extra cost.  They are using different high pressure lubricants in the newer oils instead of ZDDP but I don't trust those either since the metallurgy's are different in the newer motors.

The ZDDP levels are dropping in the HDEO's as well and it is difficult to track it.  I'm sure that right now any HDEO is fine for any vintage Caddy engine but the lighter weights are VERY hard to come by if they are made at all.  That is a problem in 10 degree weather or if you want an oil that is available off the shelf.

Therefore, I use the Valvoline VR-1 and change it more often.  I am now back to driving the car long distance so I may go back to the Mobil 1.  That 15-50 has got to be one of the best oils on the market at any price.  If your climate allows it.  It's thinner than most 50's which is why it works so well all the way down to 20 or 30 degrees as well as in the scorching temps.  Mobil 1 was it for me until they dropped the ZDDP level in their 10-30.  I believe the EP 10-30 is down to around 900 ppm now.  The standard 10-30 is at 800 ppm.

Other than the oils mentioned above it's either add ZDDP or go with a boutique such as Amsoil or Redline just to name two of them.  I need an oil I can buy off the shelf.  My Caddy doesn't sit in the garage.  For those that do in warmer climates I can't think of a better oil than Mobil 1 15-50.  The specs on it are very impressive as with the 5-40 TDT which could possibly solve my dilemma considering the radical temp changes I drive in but the 5-40 only has 1000 ppm of ZDDP although with my very low spring pressures that should be adequate now that I don't drive 5 miles each way to work in 10 degree, or colder weather.  I did notice more oil usage with Mobil 1 though.  I don't use near as much oil with the VR-1 but that could just be my engine and the fact that I have been driving it daily for over a year now whereas it sat for a week or two at a time for the previous 11 years.  Which is what it is doing once again.

Last but not least.  It is phosphorous that provides the high pressure lubricating qualities of ZDDP.  The Zinc is the carrier.
« Last Edit: April 17, 2010, 09:28:32 AM by Otto Skorzeny »

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Offline Coupe

  • Paul Flykt CLC # 18899
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Re: ZDDP in motor oil
« Reply #2 on: April 17, 2010, 09:43:18 AM »
I had read that STP would solve the problem so I sent an email to STP regarding the amount of ZDDP in their additive. They would not say how much because their formula is proprietary. They did say that there is more than enough in their product to protect flat tappet engines when added to "modern" oils.
1957 Coupe de Ville
1962 Sedan de Ville (4 window)
1993 Allante
1938 Chevrolet Business Coupe (Sold)
1949 Jeepster VJ-2

roy schroeder

  • Guest
Re: ZDDP in motor oil
« Reply #3 on: April 17, 2010, 04:56:59 PM »
Thank you guys. Sounds like I will be changing brands.
 My 78 Caddy only has 12,300 miles on it, so I dont want to start out on the wrong foot with her.
 Only had it for 7 months, and just got it out of storage .

Offline Otto Skorzeny

  • Posts: 3853
  • 1956 Coupe de Ville aka Bismarck
Re: ZDDP in motor oil
« Reply #4 on: April 17, 2010, 05:25:31 PM »
I think your 78 will be fine with any good quality, brand name, detergent oil that is rated for modern engines. 1978 is sufficiently new that I don't believe you have any real worries.

Change it at 3 months or 3000 miles.

I use Pennzoil in my '79 Ford crate engine as advised by the supplier with no additives. (Don't worry, it's in an F100, not my Cadillac)

Ask not what your country can do for you, but what you can do for YOURSELF


Offline Carfreak

  • Posts: 661
  • CLC Number: 5125
  • Name: SPashukewich
Re: ZDDP in motor oil
« Reply #5 on: April 17, 2010, 08:48:42 PM »
FWIW, just heard it again today at a club meeting, that adding ZDDP supplement is not necessary and not recommended. 
(Except during break-in when it should be used)

This time the informatoin comes from a SAE Oil Committee member who was instrumental in ensuring the current oils formulation are backwards compartible. 

Same recommendation that I heard from a GM Engineer last year (and other industry professionals) who is responsible for determining which fluids / lubricants are to be used in vehicles. 

Re: ZDDP in motor oil
« Reply #6 on: April 17, 2010, 11:45:47 PM »
Yes, I fully agree.  It's what I've been saying for several years now.  This whole "panic"
about lack of ZDDP has been blown out of proportion and makes no logical, technical or
chemical sense.  It only makes sense for those people selling the additives, who are out
to make $$$ out of this situation.

For our cars, additives are not needed.  Please put "ZDDP" in the search function and
you can read volumes about this.  I will not attempt to rehash all of it here.

As stated previously, use a quality brand of oil, API certified, and change it at least once
per year regardless of mileage or every 3,000 miles and you'll be OK.

1955 Cadillac Eldorado
1973 Cadillac Eldorado
1995 Cadillac Seville
2004 Escalade
1997 GMC Suburban 4X4, 454 engine, 3/4 ton
custom built by Santa Fe in Evansville, IN
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Offline 35-709

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Re: ZDDP in motor oil
« Reply #7 on: April 18, 2010, 09:58:07 AM »
The SEARCH function does not seem to be working.  I was going to make the same suggestion Mike Josephic did about using the SEARCH function but decided to try it first and after several minutes of waiting for my search to come up I just gave up.  This forum site has been having some problems recently, as our webmaster is aware, and apparently the SEARCH function is one of those things affected.
Geoff N.
1935 Cadillac Sedan resto-mod "Big Red"
1973 Cadillac Caribou - Sold - but still in the family
1950 Jaguar Mark V Saloon resto-mod - Sold
1942 Cadillac 6269 - Sold
1968 Pontiac Bonneville Convertible
1935 Glenn Pray - Auburn Boattail Speedster, Gen. 2

Offline TJ Hopland

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Re: ZDDP in motor oil
« Reply #8 on: April 18, 2010, 10:21:06 AM »
FWIW I just helped a friend tear down a 472 that was rebuilt in 2003.  Had 90K on it and was in a dually pickup used to haul 2 horses around the region.  He ran some sort of additive he thinks was from Comp Cams for the break in and then Havoline 10-40 conventional every 3-5K after that.  Cam still looked great as did the rest of the motor.  Was only tearing down the motor because he got a diesel truck for horse duty and is sort of doing a 'hot rod' conversion on the truck so he wants to turn it into a high compression 500.   
StPaul/Mpls, MN USA

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And other assorted stuff I keep buying for some reason

Offline PVM

  • Posts: 15
  • Name: Mikalojus Å vėgžda
Re: ZDDP in motor oil
« Reply #9 on: April 20, 2010, 11:56:21 AM »
my choice for 1975 eldo - John Deere plus 50 oil
1975 eldo convertible - 8.2 liters (500cid) will never understand, will always love.
1979 Chevy caprice station wagon 8 seater -not restored, notrepaired, but starts and drives anytime.
Guys, you were making wonderfull cars somewhere  over the ocean! (some years ago).

Tim Pawl CLC#4383

  • Guest
Re: ZDDP in motor oil
« Reply #10 on: May 17, 2010, 12:30:02 PM »
Check out the label on the back of your oil container Current standard is "SM"  ,  one of the only current containers  that I can find with the earlier standard  is Mobil 5000 conventional oil, which clearly states meets SM, SL, SK, SJ .  usages.


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