Check the maintenance schedule for your vehicle (it's in the owner's manual or a separate booklet) to see what the manufacturer requires. Chances are everything you need could be done at a competent repair shop that is more convenient or less expensive than a dealership. Don't assume, however, that a dealer will always be more expensive. They may charge $40 or less to change the oil, rotate the tires, inspect the vitals and throw in a car wash.
It is important that you recognize the difference between an EIN and a DUNS number. Although the EIN number is used to report and pay taxes to the IRS, it is not used to establish credit for your business or to report your credit history to the credit bureaus.
You are not issued a D-U-N-S Number when you apply for an EIN because EINs are issued by the IRS for tax purposes and D-U-N-S Numbers are issued by Dun & Bradstreet, for credit reporting purposes. One possible reason business owners confuse an EIN with a D-U-N-S Number is because they are both 9-digit numbers that identify a business. They are also both free numbers that can act in much the same fashion as social security number can do for an individual.