I think it is well accepted that sometimes engines produce smoke that looks blue, and I think mechanics who work on engines will confirm this. I included a personal snapshot of smoke that appeared blue to me, and a link to a video. Following a comment, I've even added several links to explanations about what may be happening in an engine to cause "blue smoke", and how to fix the problem.

As I've said in this comment "I have a strong hunch that there are some engineers who work with internal combustion engines make measurements on what is in the exhaust, and may have some insight here."

In this particular case, it seems to me that occasional blue smoke from engines sufficiently common knowledge that the question can at least stand without closing.

There are questions here that mention engine knock or backfireing, yet no acoustic spectral analyses were needed to pre-prove that these happen, before the question was allowed to stand.

Any suggestions how this question could have been asked differently so that it would not have met such resistance? Actually, is there really anything wrong with this question at all, other than the first people to read it didn't know the answer?

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First things first: I've purged the comments and migrated your question to our site for mechanics and DIY enthusiast owners of cars, trucks, and motorcycles (where it may or may not survive—as you have already noticed).

I'm sorry your question has gotten the response that it has; this is not entirely your fault. Experienced users should know that scopes are not exclusive on Stack Exchange; there are many questions that could be on topic on multiple sites and it is the author's prerogative to choose which audience they want to address.

The folks who are arguing with you about whether the smoke is blue are getting hung up on technicalities. It's a thing that engineers are known to do (often for good reason) but it's completely unproductive here. "Blue smoke" is a well-known phenomenon and a response along the lines of "the smoke is not actually blue" belongs in an answer, not in a comment or close-vote.

There are, however, some things you could have done better. Your original question on Chemistry SE was well-received with a net +2 score, despite not attracting much attention. You probably should not have cross-posted to another SE site before making an effort to better promote your original question. You could have offered a bounty on the question, for example. If you wanted to attract attention specifically from engineers, you could have posted a link to your Chemistry SE question in our chat room.

I chose to migrate this question on the off chance that it would be better received on Mechanics SE, where there are already many questions about "blue smoke"—but honestly, I think it works best where you first asked it, and if it's closed there I don't have any plans to reopen it here. I did make a few notable edits beforehand:

  1. Don't ask us to find you a study. We are a problem-solving site and the basic task of researching a topic is not an engineering problem. What you are really asking for is an explanation of a phenomenon; but it is perfectly acceptable to indicate that you prefer answers include published references. (This is good policy everywhere on SE, though not always enforced by close-votes.)
  2. You should always establish your premise at the start of the problem statement—not later on as a combative note "for the doubters." Your problem statement is not the place to have an argument. Simply state what is common knowledge; answers can address if and when the common understanding is inaccurate.

You shouldn't have been put on the defensive in the first place; that was uncivil. But in the future you would do well to disengage sooner, or avoid engaging at all, in the comments on your question. Provide what information is useful, clarify if you must—ideally in the problem statement—but avoid chatty, back-and-forth conversation.

  • $\begingroup$ Well I'm never happy with involuntary migrations as I've mentioned in my light-hearted post No Migration Without Representation! as it forces me to join another SE site to leave a comment or delete it, and starts me off on a new site on a bad foot. I didn't know of that SE's existence and I could have considered it. About engaging or not, it's hard to always be able to gauge in advance which way it will go, I try err on the side of giving the benefit of the doubt. $\endgroup$ – uhoh Jul 14 '17 at 16:14
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    $\begingroup$ @uhoh I should note that A) the users on sites that receive cross-posted questions are also rarely happy being forced to deal with them and B) your question was sitting with 4 close votes and my decision was whether to cast the 5th or migrate. I also try to give the benefit of doubt. :) $\endgroup$ – Air Jul 14 '17 at 16:22
  • $\begingroup$ Well I thought about the cross-post possibility before posting here. The Chemistry question has been there for over three months, and I think I've bumped it a few times but no helpful answer. And it is a different question, as I've only asked if there were chemicals in the smoke that caused the apparent hue "Is there a chemistry aspect to why internal combustion engine smoke is sometimes blue?". This is why I did not accept the erroneously posted answer there about particulates. So no, in this case I don't think you should say crossposting $\endgroup$ – uhoh Jul 14 '17 at 16:28
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    $\begingroup$ Anyway you did what any good moderator would do, the best overall solution to try to get the question answered and I thank you for your help. SE has limited options and that is by design and a really really good thing! I often wish for a DNR button, well, a DNM button (do not migrate) but I've nowhere near enough stamina for a feature request. Thanks for your speedy action and thoughtful answer! $\endgroup$ – uhoh Jul 14 '17 at 16:32
  • $\begingroup$ ** erratum:** in fact after checking, it looks like I have not bumped nor placed a bounty on that particular question, though I've done that to several others there. OK I'll give it a bump and if nothing happens. $\endgroup$ – uhoh Jul 14 '17 at 16:40
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    $\begingroup$ Three months is certainly enough time to wait before considering another site but what I noticed in my review was that it had only gotten about 50 views on Chemistry, which I think is the more informative metric. That's very low for a graduated site. Good luck with it going forward. $\endgroup$ – Air Jul 14 '17 at 16:55
  • $\begingroup$ You are right. Live and learn :) $\endgroup$ – uhoh Jul 14 '17 at 16:56
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    $\begingroup$ I just realized the disconnect on the last thing; my reference to three months was a comparison to the 60 day limit for migration. I should have included "...and therefore too old to ask for migration..." From time to time, mods will allow a question that is similar to a question asked in the past on a different site when good or complete answers don't seem to be forthcoming at their original site, and there's no longer any possibility of migrating the original. Not saying that applies here necessarily, just that that's what I meant. $\endgroup$ – uhoh Jul 14 '17 at 20:54

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