The problem is your website's focus is too broad.
This is currently a "thin" site. The articles are about a subject, but each page has so much information on it that the page focus is lost.
Not giving away your niche, but if your niche was "Harley Davidson motorcycle carburetors", this sites focus is on "carburetors".
You have essentially 4 articles, (three articles and a blog), and your primary navigation is Home, Privacy Policy, Contact Us, and Sitemap. This tells Google that this is the most important information on your site, and there is no real value for your visitor in this case. The secondary nav is much better.
I woud drop the very top nav bar alltogether and leave the one under the header, or move the one under the header to the top bar and drop the one under the header.
Move the privacy policy, sitemap, and about us to the footer. By the way, you need an about us page.
Since you have so much content on each page (except the "oil" page), the use of recent posts and articles in the side bar is just adding more content that is not contributing at all the the focus of the page because each of these is about a different subject, and all of it is duplicate from page to page.
You could do better with headings but I suspect that is a theme issue. You have a typo in the home page description that is I suspect is hurting traffic when your site does come up. In addition, the description is a page excerpt, and an incomplete one at that.
The description is what people see in the serps, and you need to re-write yours to invite people to click.
You may think I am saying that your site i crap, but I m not. This is a very well done site in every respect except usability and page count.
Your content is very good, far better than I expected, but you need to make more pages with less information on them. Lets take the "color" page for example. You have an article about a subject, and 5 products on the page. These 5 products link to an affiliate link for the product. This page has 1600 + words on it.
If I were you, I would change the description of each product to a summary, and link this to a newly created page about each product. On this product page, I would have the content you currently have on the "color" page, and the affiliate link.
What this will do is boost your internal linking because the "color" page will now link to 5 related pages, it will increase your page count, the individual pages may rank for the individual product, the site will not be as thin, and it will remove the affiliate links from the "color" page which can help in ranking it.
Really top notch job on the site, your mistakes are of a "not knowing better" variety, don't let me discourage you. Most sites people show me are not this good.
