Maintaining my Altima

[sunshinestateman]

Got a second-hand Altima (first car!). It's a pretty old one ('93), but it does run well

I believe I've to keep checking the engine oil every week. It does have a dipstick, but how do I know at what level I'll need to replace it?

Also, if I think of replacing it, do I drain out the old one completely? Puzzled.

[srwong]

change oil + filter every 3500 miles roughly..