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 retirement investors' portfolios.

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

Amana Growth Investor (AMAGX Quick QuoteAMAGX - Free Report) : 0.9% expense ratio and 0.62% management fee. AMAGX 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. With annual returns of 13.94% over the last five years, this fund is a winner.

Fidelity Advisor Semiconductors I (FELIX Quick QuoteFELIX - Free Report) : 0.74% expense ratio and 0.52% management fee. FELIX is part of the Sector - Tech mutual fund category that invests in technology and lets investors own a stake in a notoriously volatile sector, but with a much more diversified approach. FELIX, with annual returns of 16.38% over the last five years, is a well-diversified fund with a long track record of success.

JPMorgan US Equity Fund R5 (JUSRX Quick QuoteJUSRX - Free Report) . Expense ratio: 0.54%. Management fee: 0.4%. Five year annual return: 10.44%. JUSRX is classified as a Large Cap Blend fund. More often than not, Large Cap Blend mutual funds invest in companies with a market cap of over $10 billion. Buying stakes in bigger companies offer these funds more stability, and are well-suited for investors with a "buy and hold" mindset.

These examples highlight the fact that there are some astonishingly good mutual funds out there. If your advisor has you in the good ones, bravo! If not, you may need to have a talk.