I have a '96 2.8, great condition with 96k miles. Looking for advice from anyone relating to a strange noise I am hearing lately. ** I have been noticing that when I am in 3rd or 4th gear I notice this sort of "knocking" sound from my engine as I let off the accelorator at about 3k RPM. Sounds like a knocking or rattling - similiar to if you were to put marbles in your hand and move them around. This sound is not to be confused with the common exhaust gargle this model has. Have also noticed that I am having to add oil to my engine every month and am experiencing power loss. Have asked 5 different people and answers have varied - valve problem, cam problem, etc? Anyone have this problem? Was told to get $50 engine treatment from auto store and add during next oil change. Any other advice or answers would be great appreciated. Thanks in advance.

If the knocking sound does not occur in gears 1, 2, or 5, you may have damaged tranny and not a damaged engine.

Try lifting off the accelerator at 3000 RPM in 1, 2, and 5 and listen for something similar. If nothing, you may have a non-engine related issue. If something, you may have a chipped gear or broken/worn slider in your tranny.

Additionally, if you see oil loss at the dip stick, see if you can figure out how you lost it. Leak or consumption? Check under the car carefully for leaks, and check the exhaust pipes for soot.

Check back with some more info when you got it.

in 1,2,3 gear. One of my cats is toast... so that might be why you are hearing the rattle. Also, if the innards of the cat block the exhaust path, you will also experience a power loss...

As for oil, do what JWG said...

it would restrict flow, which could cause bad gas mileage I'm guessing... not positive on that though

a rattling noise, this was my problem when I was coasting as it was making that rattling sound. Try driving with your windows down and close to a parallel surface like parked cars or a wall in your lower gears. If your cats do rattle its time for new ones, no biggy...