Hi Bunsen, welcome to the forums!
Since you already have 2 installments, getting a personal loan won't be of any scoring benefit for you - the installment portion of your credit mix is already fulfilled. You won't see any additional rewards for your existing loans until they are paid down significantly (below 8.9%). And i dont mean paid off - paying off your loans and having them close without another installment to replace them will actually cause you to lose points - so you want your student loans to remain open for as long as possible - or at least, till you're ready for an auto or mortgage loan. In the meantime, just keep the student loan balances from exceeding their original loan amounts by paying the interest while they're in deferment, if you can.
How many revolving credit cards do you have? You need 3 revolvers and 1 installment for optimum FICO scoring. Everything else boils down to just time (letting your accounts age) and perfect payment history.