[chineseb0i]

isn't expensive..jus gear oil. U might as well change it if ur gonna add some since it's somewhat pointless to add new to oil diff fluid unless u recently had new fluid put in. Alsi check for n e leaks since ur fluid is low and we all know it doesn't magically dissappear. Easy to add..i believe there is a 1/2 inch plug near the top that u take off and from there u can add some. Correct me if i'm wrongs guys. if you plan on changing it though u can take off the plate (held by several bolts) and it all should come out. Before you put the plate/cover back on make sure both surfaces are cleaned..use a razor blade to scrape the old gasket off. Find some of that rtv/silicone/sealent stuff..high temp and squeeze a small amount around the diff and use ur fingers to spread it out then bolt it back up. Then u can add more fluid through that hole (that hole is also used to check the fluid level so u might want to do that first)

i hope this is somewhat helpful info.