As people have pointed out to me in the past, I'll pass it on. WD-40 is great for penetrating and un-sticking screws and for WD (water displacement). It's not a great general purpose lubricant, so use a lubricating oil pen instead for squeaky hinges.

My situation is pretty ideal for building credit. I just got my first credit card and I use it solely for purchases for work. I use my personal credit card for company purchases, and then get reimbursed immediately, and pay the balance on the card immediately.