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 best way to shortlist great mutual funds is to ensure solid performance, diversification, and low fees. Some are better than others, but utilizing the Zacks Mutual Fund Rank, we have identified three mutual funds that could be solid additions to one's retirement portfolio.Let's break down some of the mutual funds with the top Zacks Mutual Fund Rank and the lowest fees.If you are looking to diversify your portfolio, consider American Funds Washington Mutual Investors R6 (RWMGX). RWMGX is a part of the Large Cap Value category, and invests in equities with a market capitalization of $10 billion or more, but whose share prices do not reflect their intrinsic value. This fund is a winner, boasting an expense ratio of 0.26%, management fee of 0.22%, and a five-year annualized return track record of 10.7%.Wells Fargo Disciplined US Core Institutional (EVSIX): 0.53% expense ratio and 0.35% management fee. EVSIX is classified as a Large Cap Blend fund. More often than not, Large Cap Blend mutual funds invest in companies with a market cap of over $10 billion. Buying stakes in bigger companies offer these funds more stability, and are well-suited for investors with a "buy and hold" mindset. EVSIX, with annual returns of 10.7% over the last five years, is a well-diversified fund with a long track record of success.MFS Mass Investors Growth Stock R2 (MIRGX). Expense ratio: 0.96%. Management fee: 0.33%. Five year annual return: 14.05%. MIRGX is a part of the Large Cap Growth mutual fund category, which invest in many large U.S. companies that are expected to grow much faster compared to other large-cap stocks.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. FREE Report: The Metaverse is Exploding! Don’t You Want to Cash In? Rising gas prices. The war in Ukraine. America's recession. Inflation. It's no wonder why the metaverse is so popular and growing every day. Becoming Spider Man and fighting Darth Vader is infinitely more appealing than spending over $5 per gallon at the pump. And that appeal is why the metaverse can provide such massive gains for investors. But do you know where to look? Do you know which metaverse stocks to buy and which to avoid? In a new FREE report from Zacks' leading stock specialist, we reveal how you could profit from the internet’s next evolution. Even though the popularity of the metaverse is spreading like wildfire, investors like you can still get in on the ground floor and cash in. Don't miss your chance to get your piece of this innovative $30 trillion opportunity - FREE.>>Yes, I want to know the top metaverse stocks for 2022>>Want the latest recommendations from Zacks Investment Research? Today, you can download 7 Best Stocks for the Next 30 Days. Click to get this free report Get Your Free (EVSIX): Fund Analysis Report Get Your Free (RWMGX): Fund Analysis Report Get Your Free (MIRGX): Fund Analysis Report To read this article on Zacks.com click here. Zacks Investment Research