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 investors' portfolios.

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

Invesco Technology Fund R5 (FTPIX Quick QuoteFTPIX - Free Report) : 0.72% expense ratio and 0.58% management fee. FTPIX is a Sector - Tech mutual fund, allowing investors to own a stake in a notoriously volatile sector with a much more diversified approach. FTPIX has achieved five-year annual returns of an astounding 12.2%.

Vanguard Equity Income Admiral (VEIRX) is a stand out amongst its peers. VEIRX is a Large Cap Value fund. These funds invest in stocks with a market cap of $10 billion of more, but whose share prices do not reflect their intrinsic value. With five-year annualized performance of 11.52%, expense ratio of 0.17% and management fee of 0.16%, this diversified fund is an attractive buy with a strong history of performance.

Goldman Sachs SmCap Eq Insights R6 (GCSUX) is an attractive large-cap allocation. GCSUX 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. GCSUX has an expense ratio of 0.83%, management fee of 0.8%, and annual returns of 10.68% 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.