It is never too late to invest in mutual funds for retirement. As such, if you plan to invest in some of the best funds, the Zacks Mutual Fund Rank can provide you with valuable guidance.

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 take a look at some of our top-ranked mutual funds with the lowest fees.

Fidelity Select Software & IT Services (FSCSX Quick QuoteFSCSX - Free Report) has a 0.68% expense ratio and 0.53% management fee. FSCSX is a Sector - Tech mutual fund, allowing investors to own a stake in a notoriously volatile sector with a much more diversified approach. With yearly returns of 19.55% over the last five years, this fund clearly wins.

Tortoise MLP & Pipeline Fund Institutional (TORIX Quick QuoteTORIX - Free Report) is a stand out amongst its peers. TORIX is a Sector - Energy mutual fund, which encompasses a wide range of vastly changing and vitally important industries throughout this massive global sector. With five-year annualized performance of 7.24%, expense ratio of 0.93% and management fee of 0.85%, this diversified fund is an attractive buy with a strong history of performance.

PGIM Jennison Small Company Z (PSCZX Quick QuotePSCZX - Free Report) : 0.81% expense ratio and 0.67% management fee. PSCZX is a Small Cap Blend mutual fund, and usually targets stocks with market caps of less than $2 billion, letting investors diversify their funds among other kinds of small-cap equities. With a five-year annual return of 11.2%, 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.