First retrieve the codes stored in the computer of your car (a scan tool will be needed) to see what the code or codes stored are. Catching up with basic maintenance is a good idea for the long term good of your Buick but may not cure the problem. Consult your owner's manual to see what Buick call for on that service.Check here http://repairpal.com/automobile-owners-manuals-online or try this link you may be able to down load a free copy of the owner's manual for your vehicle http://www.autousermanual.com/
Just go to a Advance or Autozone parts house and get the PCM (computer) scanned free and make sure you ask for the trouble codes. They will be in a format like P**** something. With the trouble codes we can help you more.
As Patrick has stated it is good to do preventive maintenance but that is not going to solve your problem.