Most minor, single mouth ulcers are caused by damage to the mouth, for example by accidentally biting the inside of your cheek while eating, or from a sharp tooth, food or filling.
I have a 2005 Honda Element. The owners manual states the brake fluid should be replaced every 3 years. When I asked the dealer to replace the brake fluid, they said it was going to cost $190. I told them last time they did it, it was only $27.
Yes, definitely, regardless of whether you have a manual or an automatic transmission. Manual: Most manufacturers recommend that manual transmission fluid be changed every 30,000 to 60,000 miles. Under heavy-duty use, some manufacturers suggest changing transmission fluid every 15,000 miles. Automatic: Service intervals for an automatic transmission vary from every 30,000 miles ... to never. The typical service interval is 60,000 to 100,000 miles.