Valvetrain noise

I recently had the oil changed in my 2000 Quest. It seemed ok, but a few days later I started it and there was a lot of clacking noise like the camshafts and rocker arms under the valve covers weren't getting any oil. The oil level showed o.k. It warmed up and the noise eventually went away, but the problem keeps happening when the engine is cold. I see that some other owners recommend using lighter weight oil. It sounds like one of the oil passages is blocked. Recommendations please? Can I add something to the oil that will help it flow better?

The oil filter is probably draining when the engine is off and has to refill when it is started.

I agree. You need to be using a quality filter like a K&N filter. It has an anti drain valve built in the filter. The Nissan filter has it as well.

Thanks, I'll make sure to use such a filter when I get the oil changed again. In the meantime, I drained the new oil and put in a little lighter weight oil. It seems to have helped a lot.