It may not have an oil filter. Probably does not if its the original motor. Are you sure its a 235? It could be a 216...
Its really not a difficult process and no different than your cars.
Plan ahead so you don't make a mess. Remove the drain plug with something underneath to catch the oil. Watch till its all out.
Replace the drain plug. Remove the oil filler cap or breather cap, and poor in oil one quart at a time, checking the level using the dipstick after each quart.
Poor and check because if you dohn't know exactly what the motor is, you may not get enough oil in is just adding four or five quarts. My GMC takes eight quarts plus one for the oil filter.
Enjoy!
