Is the site only about solving etc of puzzles?
I was going to ask a question about what easy to obtain lubricants are suitable to use on a speedcube that's getting a bit sticky.
Would that be on-topic here?
I believe this question, at least categorically speaking, is on topic. I think people may be forgetting the principal mission of Puzzling Stack Exchange:
Puzzling Stack Exchange is a question and answer site for those who create, solve, and study puzzles. It's built and run by you as part of the Stack Exchange network of Q&A sites. With your help, we're working together to build a library of detailed answers to every question about creating, solving, and studying puzzles.
The site mission explicitly states questions about how to solve puzzles, in the broadest sense, are on topic. At no point in the site's history has this excluded tools and tricks for physical puzzles. Speed-solving Rubik's cubes is a category of question that fits on Puzzling, and lubrication is a critical element of speed solving. I'd say this counts. We don't get many of these questions, but that doesn't make it off topic.
That being said, since this looks like a shopping question, I'd still think actually may need some work. I'd recommend editing it to reword and ask how to properly lubricate a Rubik's cube without professional lubricant, rather than asking which one to buy - or any other way you feel like editing it to avoid the shopping nature of the question.
I would say they are on topic, yes. (As long as the puzzle-relations stays intact. When it becomes a pure crafting question, some other sites might be better.) We might need a new additional tag, though.
Originally, this site was more about puzzles (including mechanical ones) than of puzzles. The scope shifted a bit from its alpha proposal.
No, this is not on-topic.
This site is for creating and solving puzzles, and questions about that. Puzzles like this are not a good fit for this site, in my opinion.