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 retirement investors' portfolios.

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

BNY Mellon Natural Resources I (DLDRX Quick QuoteDLDRX - Free Report) : 0.9% expense ratio and 0.75% management fee. DLDRX is a Sector - Energy mutual fund, which encompasses a wide range of vastly changing and vitally important industries throughout this massive global sector. DLDRX has achieved five-year annual returns of an astounding 15.73%.

Harbor Capital Appreciation Institutional (HACAX Quick QuoteHACAX - Free Report) . Expense ratio: 0.68%. Management fee: 0.6%. HACAX is a Large Cap Growth mutual fund, and these funds invest in many large U.S. firms that are projected to grow at a faster rate than their large-cap peers. This fund has managed to produce a robust 14.97% over the last five years.

JPMorgan US Equity Fund R5 (JUSRX Quick QuoteJUSRX - Free Report) : 0.54% expense ratio and 0.4% management fee. JUSRX 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. The fund is mainly invested in equities, has a long reputation of salutary performance, and has yearly returns of 13.79% 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.