Top Kirkland-brand items only Costco insiders know

Can a brand that sells everything from baby wipes to cooking spray to ice cream to generic medicine still make high-quality products?

If you're familiar with the Kirkland brand from Costco, then you already know the answer. The wide range and prices of Costco's private label might seem too good to be true, but Kirkland brand products are the real deal.

"As a consumer, I think buying most of their products is usually a smart deal as they do have rigid quality control," a former Costco employee told GOBankingRates. "Costco has deals with the manufacturers of most of these products, who then white label on behalf of Kirkland. Because the Kirkland brand has very little money involved in the marketing of the brand, they can sell very similar products at a cheaper price."

These are some of the best Kirkland products that beat the brand-name versions when it comes to quality and price.

One of Kirkland's best-selling products is its 2-liter bottle of Italian olive oil. After a yearlong experiment sourcing olive oil in Greece, Costco returned to Italy to get its signature Kirkland brand olive oil straight from olive oil producers. The move came after sourcing issues across the industry were exposed, where it was revealed millions of olive oil consumers end up purchasing substandard olive oils that might not come from olives at all, reported industry website Olive Oil Times.

Costco corporate food buyer Shauna Lopez said in The Costco Connection newsletter that the company has taken steps to ensure its product is 100 percent Italian extra virgin olive oil. This initiative seems to have worked — Kirkland olive oil receives consistent high marks in controlled taste tests and the quality of the oil remains very high, according to Olive Oil Times. If you want to save a ton of money on groceries without compromising on quality, this is one of the best Kirkland products to consider.

Kirkland roasted mixed nuts have an impressive medley of high-end nuts: almonds, cashews, macadamia, Brazil, and pecans. In addition to their high quality and extra-fancy grade, the Kirkland mixed nuts often beat competitors prices, too. A 2.5-pound 2-pack of Kirkland mixed nuts costs less than a similar product from Trader Joe's, another company famous for its high-quality white-labeled products. You can even buy Kirkland brand mixed nuts on Amazon or at Walmart, but it will still cost you more than if you bought directly from Costco.

In a test comparing multiple brands of AA batteries, Consumer Reports found the Kirkland Signature AA batteries were the best bargain, keeping up with Duracell in toy tests — at about half the price. These high reviews make sense, as our Costco insider revealed Kirkland batteries are manufactured by the same company that makes Duracell batteries.

"I don't know if it's the same formula," he said. "But Costco charges Duracell large fees for prime positioning in their stores (endcaps), and on top of their huge marketing budget I'd imagine you're paying a premium for a very similar battery."

Baby wipes have a variety of uses, but one thing's for certain: They need to be gentle on sensitive skin. Kirkland Signature baby wipes get consistent reviews from customers for their ultrasoft, hypoallergenic materials that contain 70 percent Tencel fibers, which are infused with aloe and chamomile. These top-rated baby wipes are also free of alcohol, parabens, and chlorine.

Over 700 shoppers have reviewed the Kirkland baby wipes, which have nearly a four-star rating out of five possible stars. Costco member "mommyliz" wrote, "These are the best quality baby wipes on the market I've come across. Along with quality, the price can't be beat (especially on sale)."

Good Housekeeping rated Kirkland Signature supreme diapers as "The Club Champ" in its battle of the best baby diapers, and Reviews.com named them one of the best diapers on the market. They are one of the most affordable, too.

Our Costco insider couldn't reveal which manufacturer makes this item for Kirkland, but it's rumored the diapers are nearly identical to Huggies. On Mamapedia, a forum where parents can swap parenting advice, user "C.D." said, "The company my husband works for, Kimberly-Clark, makes Kirkland Signature Diapers. They are basically the same as Huggies, with only a slight variation. So, if you like Huggies, you will like Kirkland Signature diapers."