Is there any other lubricants that need to be checked in a 2003 Honda VTX 1800?

Yes, there is other oil to check than just the engine oil. You need to check the oil for the cardan drive shaft on this bike. Use good grade gear oil for this, for example Amsoil's "SVG" 75W-90. The final shaft drive contains 4.1 ounces or 120 cc of gear oil. The fill and drain plug are close to each other, the fill plug is a bit higher up. Use a 17 mm wrench on both. Don't worry ig you fill a bit more oil than is needed as an automatic vent will dispose of the extra oil. Check the drive shaft area after an oil change, and wipe any extra oil off with a soft cloth.