This is definitely a question for a good local juvenile attorney in California. You may be able to find a local one at www.lawyers.com.
To my knowledge, there is no way to seal a conviction on your driving record. The DUI conviction will most likely remain on your public DMV record for 10 years from the date of conviction. You can petition the court to seal the juvenile criminal "true finding," (conviction), but that will not effect your DMV record. The only way to remove something from your DMV record would be to get a "Statement of Factual Innocence" which is probably impossible to get since your were convicted.
Never discuss confidential information on a public website. Always speak with an attorney in a confidential setting.
The above response is not intended to create an attorney-client relationship. The information offered in this response is for general informational purposes and is not a legal consultation. You must talk with an attorney of your choice before making any decision about your actual legal rights.
I agree with Mr. Stuart. You cannot seal your traffic record, even though your juvenile record will automatically be sealed. So, while your juvenile record cannot be found by non-criminal justice personnel, your traffic record can. You should, nevertheless, consult with and potentially retain counsel to determine if there could be a way to seal or remove just the DUI conviction from the traffic record. Creative arguments based upon existing law, i.e. juvenile code, may usually be made and a Court just could be convinced to order DMV to seal it due to your status at the time as a juvenile. Likely, however, this cannot be known until tested by a litigant such as yourself.
The information provided herein does not create an attorney-client relationship. The information provided is to suggerst some general principles and should not be relied upon for client decisions. Only upon the hiring of counsel can such advice be custom-tailored to the client's specific situation and needs.