Like the title says, this is a dumb question but I’m new to working on my car so I hope someone can give me some advice.
I have a PT Cruiser that I’m in charge of maintaining. It uses 5W-30. There was a sale on 10W-40 so I bought some. I understand you are not supposed to mix oil grades. Here is the question, when you drain your old oil there is always some oil left in the pan, right? How much is too much leftover oil before I add the new grade of oil?
So, I guess the question is, should I do anything special before adding the new oil?