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.

Here are the funds that have achieved the Zacks Mutual Fund Rank #1 (Strong Buy) and have low fees.

ASG Managed Futures Strategy Y (ASFYX Quick QuoteASFYX - Free Report) has a 1.48% expense ratio and 1.25% management fee. ASFYX is an Allocation Balanced mutual fund. Allocation Balanced funds look to invest across asset types, like stocks, bonds, and cash, and including precious metals or commodities is not unusual; these funds are mostly categorized by their respective asset allocation. With yearly returns of 10.52% over the last five years, this fund clearly wins.

Great-West Multi Manager Large Cap Growth (MXLGX Quick QuoteMXLGX - Free Report) . Expense ratio: 1%. Management fee: 0.64%. MXLGX is a Large Cap Growth option; these mutual funds purchase stakes in numerous large U.S. companies that are expected to develop and grow at a faster rate than other large-cap stocks. This fund has managed to produce a robust 13.26% over the last five years.

Virtus KAR Small-Cap Core A (PKSAX Quick QuotePKSAX - Free Report) is an attractive large-cap allocation. PKSAX is a Small Cap Blend mutual fund, allowing investors a way to diversify their funds among various types of small-cap stocks. PKSAX has an expense ratio of 1.25%, management fee of 0.75%, and annual returns of 13.53% over the past 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.