On the CRF450R, the engine oil drain is found on the ignition cover on the left-side case (10mm bolt), and the transmission oil drain hole is on the left-side crankcase behind the shift lever (12mm bolt). When it’s time for an oil change, always change both oils!
STEP 1: Before getting started, make sure that you’ve got everything you’ll need to get the job done, including engine oil and transmission oil (check your owner’s manual for the proper grade and quantity of each), a new oil filter, an 8mm T-handle to get to the filter, a 10 and 12mm T-handle wrench for the drain bolts, an oil drain pan, a triangle stand and a 10mm Allen wrench for the primary gear inspection window (optional).
STEP 2: I recommend starting your bike and running the engine for a minute or two before draining the oil. Running the bike will heat the oil slightly, making it less viscous so that it will drain out more efficiently. I generally use a triangle stand rather than a box stand to hold up the bike to leave more room to work when draining the oils. Place your oil drain pan directly under the oil-draining hole that you empty first.
NOTE: Steps 3 & 4 can be done simultaneously.
STEP 3: Using your T-handle, remove the engine oil drain plug and allow the oil to drain into the pan.
Tip: Because oil gets trapped underneath the piston, once you think the draining is just about completed, I always recommend holding the kill button and gently kicking the bike over about five times. This will help to remove the trapped oil. Be prepared, however, as oil will shoot out of the drain hole and all over your garage floor if you’re not careful.
Now, put the drain bolt back in and tighten it appropriately.
STEP 4: Using your T-handle, remove the transmission oil drain bolt and allow the oil to drain into your pan. Put the drain bolt back in and tighten it appropriately.
STEP 5: To access the oil filter you’ll first need to remove the engine guard. Remove the 8mm filter cover bolts with your T-handle, and pull the cover off. Pull the filter out and inspect it for metal shavings. Your oil filter acts as a sight glass into your engine. If you find more than just a couple small shavings, I recommend visiting your local dealership for a consultation. With your new filter in hand, be sure to place the spring in the slot at the end of it, and slowly slide it into the motor, lining up the other end of the spring into the slot on the inside of the case.
STEP 6: Now it’s time to fill your bike back up with fresh engine oil. The engine oil is poured directly into the filler hole located on the top left side case (ignition cover).
STEP 7: The last step is to quench your bike with fresh tranny oil. With a stock head pipe you can pour the oil into the fill hole located on the right side of the engine. If you have an aftermarket exhaust that features a drop-down head pipe, however, here is a little tip. Using a 10mm Allen wrench, remove the primary gear inspection cover that is located just below the fill hole. With the bike leaning on its side you can fill the transmission oil into this hole without having to remove the head pipe.
Got this from another website, no credit to me, just found it for you.