hello everyone,i work at at a local transfer station and we had a HAZ-MAT day and a guy turned in about 30 cans (yes cans) of old oil never opened.old STP mobil and so on.my question is can i still use it? it says 10w-30-40-50 on the cans.never seen anything like that before.thanks again.this forum is the best by the way,learned a lot here.