zinc in motor oil

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bakerallen
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Joined: Wed Aug 09, 2017 2:42 pm

zinc in motor oil

Post by bakerallen » Tue Nov 27, 2018 8:33 am

I have a question about motor oil. I have a 47 Packard with a recently rebuilt small 8 cylinder. The car has been run very little since the rebuild. Less than 100 miles. Should I worry about the zinc content of the oil, or would any quality oil contain enough to prevent damage. Also what weight should I use. I remember when the cars were in common use. I never owned a Packard, but I did own other cars of the same age, and I always used 30 weight oil, and never had any problems. I plan on doing the same with this engine unless some one has a better idea. I imagine the oils available in the mid 40's had low or no amounts of zinc in them so it seems any modern quality oil of the proper weight would still contain enough zinc. Any thoughts will be appreciated.

Dave Czirr
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Re: zinc in motor oil

Post by Dave Czirr » Tue Nov 27, 2018 9:11 am

First of all, the zinc additive myth, it is unnecessary and irrevelant for your Packard engine, engines that need it are those with high loading on the cam lobes and tappet bodies like modern high compression OHV V8 engines. That said, won't help, but can't hurt. So what's more important is to avoid too heavy an oil and to use a major name quality detergent oil. Heavier oils move more slowly, take longer to get to where they're needed on startup, and are poorer at heat transfer. Starting with a clean engine, you want to keep it that way. So my choice with a nice fresh engine would be a quality SAE10W-30. If you're going to be hauling a heavy trailer regularly or planning on a steady diet of 70+mph speeds, or use where normal temperatures are typically 100 deg. F. or higher, I might consider a SAE15-40.

bakerallen
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Joined: Wed Aug 09, 2017 2:42 pm

Re: zinc in motor oil

Post by bakerallen » Wed Nov 28, 2018 8:02 pm

Thanks for the reply. Honestly, until recently I never heard of zinc in motor oil A friend mentioned it to me, and I looked it up on the internet, where I found all kinds of advice telling me my motor would be ruined if I didn't address the problem. I thought that was strange because this is the third old motor I have had rebuilt and none of them have had any additive other that a quality motor oil with no problems. I have already purchased a bottle of the additive. Since I have it, I am going to use it and then forget about it. My car needs a few small things, and then I hope to begin using it. This has been a long and aggravating journey and I am looking to forward to finally seeing the light at the end of the tunnel.

Adam
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Location: lincolnshire, uk

Re: zinc in motor oil

Post by Adam » Thu Nov 29, 2018 5:18 am

Definitely follow Dave`s advice regarding viscosity (although the more common form would be SAE 15W40 here, despite there being zero chance of 100 degree F temperatures).

Look for an oil with API SG/CF4 designation, or thereabouts. That is a mineral oil blended for petrol or diesel cars or trucks of the 1990s or early 2000s. SG is fine for petrols with catalytic convertors, even turbocharged. CF4 indicates a high detergent content for diesels. But it is not suitable for diesel particulate filters (too much ash and zinc).

That oil will be cheap to buy and it will keep your newly built engine clean and healthy for several lifetimes! Change it once a year for best effect.

You will find it locally, but here is an example from my local blender:-
https://www.withamgroup.co.uk/shop/engi ... s/ef15w40/
"Do not underestimate the English cousin.....they are not as stupid as they look!" - Signor Altabani in The Italian Job.

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