Adam my man, there is a fill plug on top and a oil level plug on the side. I kept mine at least an inch over the side plug (guessing of coarse) If you fill to full used to cause foaming and oil would come out the top breather hole and drip on the carpet and give you more headaches if you don't catch it every drop or time.. I never used synt. but agree a better oil than reg. I used 30 wt non detergent..