There is never a wrong time to invest in mutual funds for retirement. So, if you're still looking for the best mutual funds, the Zacks Mutual Fund Rank can be a great guide.

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.

Here are the funds that have achieved the Zacks Mutual Fund Rank #1 (Strong Buy) and have low fees.

Neuberger Berman Social Responsible R6 (NRSRX): 0.57% expense ratio and 0.54% management fee. NRSRX is a Large Cap Value fund. These funds invest in stocks with a market cap of $10 billion of more, but whose share prices do not reflect their intrinsic value. With annual returns of 14.82% over the last five years, this fund is a winner.

American Funds Fundamental Investors R1 (RFNAX): 1.36% expense ratio and 0.24% management fee. RFNAX is part of the Large Cap Blend section, and these mutual funds most often invest in firms with a market capitalization of $10 billion or more. By investing in bigger companies, these funds offer more stability, and are often well-suited for investors with a "buy and hold" mindset. With yearly returns of 13.44% over the last five years, RFNAX is an effectively diversified fund with a long reputation of solidly positive performance.

DFA Selectively Hedged Global Equity I (DSHGX Quick QuoteDSHGX - Free Report) . Expense ratio: 0.3%. Management fee: 0.24%. Five year annual return: 12.36%. DSHGX is a Global - Equity mutual fund, which invests their assets in large markets, leveraging the global economy.

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.