It is never too late to invest in mutual funds for retirement. As such, if you plan to invest in some of the best funds, the Zacks Mutual Fund Rank can provide you with valuable guidance.

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 break down some of the mutual funds with the top Zacks Mutual Fund Rank and the lowest fees.

Invesco SteelPath MLPSelect 40 R6 (OSPSX Quick QuoteOSPSX - Free Report) has a 0.93% expense ratio and 0.69% management fee. OSPSX is classified as a Sector - Energy mutual fund. Throughout the massive global energy sector, these funds hold a wide range of quickly changing and vitally important industries. With yearly returns of 28.64% over the last five years, this fund clearly wins.

Thornburg Global Opportunities I (THOIX): 0.99% expense ratio and 0.84% management fee. THOIX is a Global - Equity mutual fund, which invests their assets in large markets, leveraging the global economy. With yearly returns of 16.59% over the last five years, THOIX is an effectively diversified fund with a long reputation of solidly positive performance.

American Funds Growth and Income Portfolio R1 (RGNAX): 1.09% expense ratio and 0% management fee. RGNAX is a Large Cap Blend fund, targeting companies with market caps of over $10 billion. These funds offer investors a stability, and are perfect for people with a "buy and hold" mindset. The fund is mainly invested in equities, has a long reputation of salutary performance, and has yearly returns of 10.68% over the last 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.