Is this oil right for a wet-clutch motorcycle?

Only if your manual calls for a 20W-50 and does not require a JASO MA or MA2 rating. The jug does not state a wet-clutch friction rating, so check the owner's manual before using it in a motorcycle with a wet clutch.

How is it different from Valvoline conventional 20W-50?

The full synthetic base resists heat breakdown and sludge better and holds its viscosity longer. Conventional oil is fine for mild use, but the synthetic is the better pick for air-cooled engines and hot climates.

Can I use it in a car or truck?

Only if the owner's manual specifies 20W-50. Most modern cars call for thinner grades such as 0W-20 or 5W-30, and using 20W-50 in those engines can hurt cold-start flow and fuel economy.

How much oil does one jug hold?

One US gallon, which is 128 fluid ounces. That covers most motorcycle and small-engine oil changes with some left over for top-offs.

How often should I change it?

Follow the interval in your owner's manual. Full synthetic oils often allow longer intervals than conventional, but dusty, hot or hard-riding conditions call for shorter ones.