Hey seiyak2009, what happens when the business just decides to record the oil price every 5 seconds due to a new fast trading platform introduced at the company? Your trigger is now sending thousands of emails crashing both SQL and the Exchange server.
Don't send emails from triggers. Use a procedure which can be configured for a set time interval to check the oil price table, then generate an email. (I'd also hesitate sending any non critical alert emails from SQL itself. Business functionality should not be built in the data layer.)