I bought refurbished front CV axles from both O'Reillys and Autozone. Put them both on at the same time. The Autozone axles went out in 30,000 miles. The O'Reillys axles are still going strong. Apparently Autozone uses chinese axles, according to O'Reillys. If you wait until they start making noise, it is too late to just add grease. Auto mechanics will smear brake fluid on the rubber so that they crack in 30 days, simultaneously. So then it's back to the auto mechanic again. Funny how that works. Tip: stuff as much axle grease into the wheel bearing area as you can because it helps with the longevity of the wheel bearings. Pressure wash the inside of your brake area so that you don't get dirt into the wheel bearings when you go to reinstall the cv axle.