Last month when I got my oil changed they told me their was no oil on the dipstick. My engine had never used excess oil so I didn't check it. Now my engine is tapping softly all the time. Is this usually serious? I am checking my oil every week now and it isn't going down any. It is a 2004 Expedition with 96.000 mile's on it. I have alway's gotten the oil changed every 3,000 mile's and this last time I let it go about 4500 mile's. Obviously big mistake. I am a 64 year old cleaning lady so I am very nervous about this ticking or tapping.