1991 Chevy Camaro ticking noise coming from the engine

I have a 91' Chevy Camaro and I have a ticking noise that seem to be coming from the engine. The car has about 103,000 miles on it and the service engine light has come on twice, but doesn't stay on long. The ticking is quiet until you go over 35-40mph then it gets louder and faster. Also the oil monitor in the car where it tells you how much oil is in the car went off track when it started doing that the little hand just jumps back and forth. What can possibly be the problem. Your oil moniter is just a guage that gives you approximate oil pressure, not the amount of oil in the car. Check the oil level with the dipstick first. If it is low add oil until it reaches the full mark. If it still ticks after that, have the oil pressure checked with a manual pressure guage. If oil is full and guage reads low pressure, the oil pickup could have sludge in it or the oil pump may be failing. Let us know what you find out.