There is never a wrong time to invest in mutual funds for retirement. So, if you're still looking for the best mutual funds, the Zacks Mutual Fund Rank can be a great guide.

The easiest way to judge a mutual fund's quality over time is by analyzing its performance, diversification, and fees. Using the Zacks Mutual Fund Rank of over 19,000 mutual funds, we've identified three outstanding mutual funds that are ideally suited to help long-term investors pursue and achieve their retirement investing goals.

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

Fuller & Thayler Behavioral Small Cap R6 (FTHFX Quick QuoteFTHFX - Free Report) : 0.63% expense ratio and 0.6% management fee. FTHFX is a Small Cap Blend mutual fund that usually targets companies with a market capitalization of less than $2 billion. FTHFX has achieved five-year annual returns of an astounding 13.98%.

Oppenheimer SteelPath MLP Select 40 I (OSPSX Quick QuoteOSPSX - Free Report) . Expense ratio: 0.83%. Management fee: 0.7%. OSPSX is a Sector - Energy mutual fund, which encompasses a wide range of vastly changing and vitally important industries throughout this massive global sector. This fund has managed to produce a robust 11.89% over the last five years.

TIAA-CREF Lifestyle Aggressive Growth Retirement (TSARX Quick QuoteTSARX - Free Report) . Expense ratio: 0.35%. Management fee: 0.1%. Five year annual return: 10.72%. TSARX 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.

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.