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 learn about some of Zacks' highest ranked mutual funds with low fees you may want to consider.

Fidelity Trend Fund (FTRNX Quick QuoteFTRNX - Free Report) has a 0.55% expense ratio and 0.41% management fee. FTRNX 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. With yearly returns of 11.07% over the last five years, this fund clearly wins.

Red Oak Technology Select (ROGSX Quick QuoteROGSX - Free Report) . Expense ratio: 0.94%. Management fee: 0.74%. ROGSX is a Sector - Tech mutual fund, allowing investors to own a stake in a notoriously volatile sector with a much more diversified approach. This fund has managed to produce a robust 10.31% over the last five years.

Ivy Large Cap Growth A (WLGAX Quick QuoteWLGAX - Free Report) : 0.93% expense ratio and 0.61% management fee. WLGAX 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. The fund is mainly invested in equities, has a long reputation of salutary performance, and has yearly returns of 11.96% over the last five years.

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.