My car will be paid off in 3 months, can I use the Secured Loan Technic to add installment loan for the car?
Yeah. Assuming this car loan is your only open installment loan, then it's a good idea to implement the SSL technqiue in the next couple months. That way your installment utilization will stay really low after the car loan is paid off. And assuming you get a 60-month loan with Alliant, it'll stay that way for five years.
PS. Welcome to the forums!