I bought some oil the other day so I could change it while I had the car up on the lift this weekend. I bought Castrol Syntec synthetic blend cause it was on sale and they didn't have Mobil 1. I was thinking I grabbed 5W30 but apparently I picked up 5W20. I didn't realize it until I started to put it in the car(the old was already out and disposed of). So I had to use it since it was 4am and I needed to get the car out. Am I going to be alright or should I buy the right stuff and switch it out asap? I don't know a whole lot about oil weights. Thanks

 

IT wont hurt the engine.......

 

I would have to disagree..... GM specified 5W-30. The people who have taken the time to have their used oil analyzed have found that even Mobil 1 5W-30 is a little on the thin side for the LT1 ("search" for posts by Patman). Dropping down to a "thinner" (= less viscous) 5W-20 in hot weather could lead to failure of the oil film that the bearing surfaces ride on. For "normal" driving, you won't hurt anything, but I wouldn't put the engine under max load with that oil in it.