Tide is a good, strong detergent that works well and is available everywhere. If you want to avoid a scent, use Tide Free, though it isn't necessary. The Mexican version of Ariel detergent (available at a Latino grocery) is a strong soap that works well, too, although the scent is fairly powerful for the uninitiated.
You can use regular -- fabric softener free -- detergents to wash MF with no problems. The keys are (1) using about half the soap you think you need; (2) washing MF with other MF products and no lint producers like regular cotton towels; (3) using VERY hot water; (4) using a second rinse cycle if your washer has one; and (5) drying without fabric softener. Oh, one more key: throw away MF towels (or banish them to rims, door jambs, etc.) after they get old or too dirty to clean and are no longer good enough for your paint.
If you have a front-load washer with water heater / sanitary cycle, use it at the hottest setting. Some of the front-loaders can make the water just short of boiling, which is great to clean MF.
If you normally use dryer sheet fabric softeners, the inside of your dryer is probably coated with the waxy fabric softener stuff, and that could get on your MF towels, making them less soft and absorbent, unfortunately.
330i | Black Sapphire | Beige + Burl | Sport | Premium | Cold | Nav | CA | Sat prep