Using a "Cashiers Check" is no gurantee to the dealer.
Yes, 'even though it came from my...(Bank, credit union, mother,'!
If you give someone a cashiers check for a purchase;
up to and until they cash it, all you have to do is call the bank and say you dropped your check in the street and it went down a storm drain or some other excuse and show them your copy of the check and they will stop payment on that check before you can say Bob's your uncle.
If you think that your SS number is secure just do a public record search on yourself some day.
Remember the pimpley faced kid that made you fill out a credit app for that cell phone in your pocket. He has your number and one of the reasons that cell phone stores get robbed is to get the totally unsecure information that is literally hanging out of the files in the back of the store. ps they also have your credit card information on that app remember.
Oh, by the way. When you got the credit thing last christmas at Kohl's so you could get 20% off, they have your SS#. So do all the other credit card companies that recently were hacked for that information.
You are not secure.
(By the by. Your ISP also has a record of EVERY website you ever went clicking to.)