Investing in mutual funds for retirement is never too late. And the Zacks Mutual Fund Rank can be an excellent tool for investors looking to invest in the best funds.

How can you tell a good mutual fund from a bad one? It's pretty basic: if the fund is diversified, has low fees, and shows strong performance, it's a keeper. Of course, there's a wide range, but using the Zacks Mutual Fund Rank, we've found three mutual funds that would be great additions to any long-term investors' portfolios.

Let's take a look at some of our top-ranked mutual funds with the lowest fees.

Voya Large Cap Growth A (NLCAX): 0.9% expense ratio and 0.51% management fee. NLCAX is a Large Cap Growth option; these mutual funds purchase stakes in numerous large U.S. companies that are expected to develop and grow at a faster rate than other large-cap stocks. With annual returns of 9.48% over the last five years, this fund is a winner.

Bridgeway Omni Small Cap Value Fund (BOSVX Quick QuoteBOSVX - Free Report) : 0.47% expense ratio and 0.45% management fee. BOSVX is a Small Cap Value mutual fund option, which typically invest in companies with market caps under $2 billion. With yearly returns of 12.21% over the last five years, BOSVX is an effectively diversified fund with a long reputation of solidly positive performance.

American Funds New Economy 529A (CNGAX) is an attractive large-cap allocation. CNGAX is a Global - Equity mutual fund. These funds invest in large markets like the U.S., Europe, and Japan, and operate with very few geographical limitations CNGAX has an expense ratio of 0.76%, management fee of 0.36%, and annual returns of 11.8% over the past five years.

There you have it. If your financial advisor had you put your money into any of our top-ranked funds, then they've got you covered. If not, you may need to talk.