Is this true?: Zinc taken out of oil/ruining old engines?


Old 12-27-07, 05:02 PM
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Is this true?: Zinc taken out of oil/ruining old engines?

JUST got off phone with landlord I do work for who is in a classic auto club who said one of the topics of their discussion in their last meeting was about what to do, and what is going on with oil manufacturers who have now stopped putting zinc additive in oil, supposedly as it was harming cats, and now people are finding out it is ruining their upper valve trains in collector cars.

Supposedly he said the oil companies took the zinc out about less than a year ago, and no additional labeling was put on the oil bottles.

Supposedly the metals in new cars are made to withstand zinc-less oil? But that leaves older cars without the needed protection?

And he said that to their knowledge, there is no zinc additives on the market. (Like there was when they took lead out and there were lead substitute additives you could add.)

Does anybody know anything about this? Is this true? Internet fabricated rumor? Or What?

Last edited by stickshift; 12-27-07 at 07:13 PM. Reason: Requested by poster
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Old 12-27-07, 06:48 PM
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No idea; some info on zinc compounds in engine oils here:
I'm not worried about it; too many other issues in this world to keep me occupied. I'm sure the oil is fine with/without the zinc; something else will be added to meet standards if need be.
Old 12-28-07, 06:20 AM
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Old 12-30-07, 08:00 PM
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Yes, it's true
It was an EPA mandate, as the zinc was messing with the newer (cheaper made) catalytic converters

In older engines, especially flat tappet engines, the lack of zinc can lead to early engine failures
It's especially tough during the critical break-in period after a new cam or yeah, there have been a lot of unhappy customers having engines fail right after having work done

A common fix is using diesel oils, exempt from the EPA decree
Also I have heard from several trusted sources that Rotella T is a good option, though I have not verified that
Old 12-31-07, 11:25 AM
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I'm somewhat on top of this, since I have an old muscle car that is kept stock. It's the new oils with SM ratings that you have to worry about. Right now I'm using a diesel-rated oil (Rotells T 15W-40). I'm not to keen on using 15W-40 for my climate and driving pattern (short trips), so I have a supply of SLOB oil additive to add to regular oil.

If you have a modern engine with roller tappets, you have no worries.
Old 12-31-07, 04:07 PM
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Thanks very much you guys. Just got in the door from working all day at a rental getting it ready and came here first and was glad to see these responses, and so I called the landlord right up moments ago and read him the last 2 posts (also website addresses below that) and he is most happy with the info. Plus I said, that since the printer is down, I am going to write those several websites down that were provided by 2 posters below and give them to him so he can research those also.

Thank you very much. And HE thanks you.

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