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.

Columbia Contrarian Core Z (SMGIX): 0.73% expense ratio and 0.6% management fee. SMGIX is a Large Cap Value mutual fund, which invests in stocks with a market cap of $10 billion of more, but whose share prices do not reflect their intrinsic value. SMGIX has achieved five-year annual returns of an astounding 12.64%.

Boston Partners Global Equity Institutional (BPGIX Quick QuoteBPGIX - Free Report) : 0.95% expense ratio and 0.9% management fee. BPGIX is a Global - Equity mutual fund investing in bigger markets like the U.S., Europe, and Japan; these kinds of funds aren't limited by geography. BPGIX, with annual returns of 11.98% over the last five years, is a well-diversified fund with a long track record of success.

Goldman Sachs MLP Energy Infrast R6 (GLPSX): 1.04% expense ratio and 0.96% management fee. GLPSX is a Sector - Energy mutual fund, which encompasses a wide range of vastly changing and vitally important industries throughout this massive global sector. With a five-year annual return of 18.75%, this fund is a well-diversified fund with a long track record of success.

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.