I had been using the Gunk lead substitute in my 69 Dart, but just discovered that I have an old bottle of the CD2 lead substitute sitting around that was started a long time ago but almost unused. I probably bought it ten years ago or more. Does this stuff age? Is it okay to use?

By the way, I know a lot of people think for most purposes lead subsitutes are unnecesary. I've read the other threads on this. I've been using it on the recommendation of my mechanic (who is somebody who only works on and restores pre-1975 cars, so I'm willing to give his opinion that the substitute does some good creedence).

I'm just curious if this old bottle of CD2 could have "gone bad" in some way or lost it's effectiveness. Thanks.

Using it will be the quickest and easiest way to dispose of it safely.
It's not that people "think" it, it's that it's true. You do not need lead substitute in your Slant-6.
...who is wrong, at least in the case of the Slant-6. All you are doing is wasting money and hastening the fouling of your spark plugs. Stopping would be an excellent idea.

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

HI SlantSixDan,

Thanks for the response. I have read your long post on this subject elsewhere in this forum.

I'm more or less convinced, by what you've said. But as I mentioned, my mechanic is not just some mechanic. He really is an expert on these cars and does nothing but work on them and restore them to perfection. So I am caught a bit between two people who disagree, seem to be extremely knowledgeable, but are giving me different advice.

I guess my understanding is that under heavy load there is some benefit. I've never had an issue with the spark plugs. On the other hand, I only put about 500 miles, or less, on this car a year, so it might take decades for the plugs to be "prematurely" fouled. Of course, I suppose one could also say whatever small benefit there might be to the valves from the lead substitute will also take decades to show up, so why do anything?

I guess I'll revisit this question when I'm done working my way through the bottle of CD2 (which may also take decades).

I do appreciate your response and your many other informative posts in this forum. I learned a lot about oil from you!

Cb

Neither is "Tommy", the sincerely-believed guy described here. And yet…! I'm not saying I know everything and everyone else is wrong -- it's that people who are experts in old cars in general don't necessarily know the little-detail particulars of the Slant-6. Yes, the exhaust valves on many pre-1972 engines will wear fast if the engine is operated on unleaded for prolonged periods, but the Slant-6 has particularly well-cooled exhaust valves and so there's no worry except in very heavy-duty service. Also, it's 2015; the overwhelming majority of pre-1972 engines (of any/all type) have been rebuilt at least once, and the minor, easy modifications for 100% long-term compatibility with unleaded fuel have been standard practice in a cylinder head overhaul for many years now.
He's a Slant-6 expert? I doubt it. If he were, he would know that lead substitute is not necessary.
which is super-light-duty service, adding even more weight to the "lead substitute not needed" case.
Glad to help out.

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

I've heard it suggested that valves will start "sinking" into the valve pocket when using unleaded fuel in a head without hardened seats.

If this is true, Would the lead substitute work to prevent it?

Please read the post immediately above yours, and this.

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

Thanks for the further details.

The Slant-6 in my Dart is in fact the original engine (with 150K on it). My parents were the original owners, so I know its entire history. The engine has never been rebuilt, overhauled, or modified. It sounds like you're still saying it doesn't matter and the lead subsitute is unnecessary, because the valves are well cooled due to the original design.

My mechanic, as I said only works on pre-1975 cars and he does seem, in my interactions with him, to be as knowledgeable about these engines as you seem to be. He has fixed things on the car and known things about fluids, that no one else has ever come close to understanding, who worked on the car in the past couple decades. I don't expect you to change your opinion or understanding of this issue, based on my assertions about some mechanic you don't know--that wouldn't make any sense for you and I'm not trying to convince you. And I'm open to the possibility that you may well know more about the Slant-6 than my mechanic. I was only pointing out for someone in my position who has two seemingly extremely knowledgeable people telling him slightly different things (though not that different), it is not obvious how to judge that.

In any case, it doesn't sound like I'm really going to go terribly wrong either way here. And, again, I do appreciate your input and detailed explanations and value your knowledge on all things Slant-6.

I also was not trying to restart the lead substitute debate, because, as I said above, I already read your lengthy explanation of the issue in another thread in this forum, before starting this thread. My question was simply, if I go ahead and use the CD2 anyway (however misguided that may be), is it possible a ten year old opened bottle may have "gone bad" in some way and should just be disposed of (at a proper toxic waste collection site).

Thanks Dan, That link was helpful in learning more about my cars .

I just helped a friend disassemble a 1965? block which must have been rebuilt quite awhile ago , That explains why the valves where sunken.

I had a 70 Maverick I6 that did burn exhaust valves. Dan please confirm my understanding that the problems only involved exhaust valves. Thanks.

Sam

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In normal conditions, and not hot engine running or lots of long hill/mountain pulls, you will be fine without lead or substitute. If you raise compression or run hot, then you will erode the exh valve seats. The easy fix is stainless valves.

Lou

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Home of Slant6-powered fun machines since 1988

On every engine I've ever had rebuilt, I've always had hardened seats installed on the exhaust - just to be on the safe side. The current engine I am working on - a 65 slant with less than 70,000 miles - had quite a bit of valve seat recession.

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65 Dart station wagon slant 6 - now under construction
47 Dodge Custom 4 Door sedan
87 D100 Short Bed slant 6

Retired USAF 1966-1986
Retired US Postal Service 2004-2014

The other half of this, which seems to be getting not much attention, is that most of the commercially available lead substitute additives don't tend to do much to prevent exhaust valve recession.

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

…which means it's likely somewhere between "almost due" and "overdue" for a rebuild anyhow, at which time install hard exhaust valves and seats in the head.

Until then, do as you will (it's your car), but a bottle of additive is not a fountain of youth for your engine. You really, truly do not need it, but if makes you feel good to use it…it's up to you.

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

Rebuild, really? I thought it was normal for these engines to easily get over 200K? I thought that was part of the mystique of the mighty Slant 6. No?

(And yes I definitely plan to do the hardened exhaust valves when the time comes. Although at 500 miles/year I wonder if that time will ever come. I'm not getting any younger! My mechanic also told me my Slant 6 is the smoothest running one he's seen, so hopefully that is a sign that it has had a gentle life and is not imminently in need of a rebuild.)

Anyway, I basically believe you on the lead substitute. And I take your point that they don't even do that much, regardless of whether they're necessary. I only mentioned my mechanic, etc., to explain why I was doing what I was doing, even though I read your posts and probably should know better. Like I said, I'm not trying to debate your expertise on the matter or convince anyone else.

Thanks again for the thoughts and replies.

Valve seat inserts may not be necessary (unless they're recessed)


Start reading here:

http://slantsix.org/forum/viewtopic.php ... eat#415239

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Ed
64 Valiant 225 / 904 / 42:1 manual steering / 9" drum brakes