[JimD]

I am not trying to imply that the engines with ticking sounds are worn out due to infrequent oil changes. I am only saying that relatively high mileage oil is thinner. My theory is that the oil pressure is not being maintained in the lifters at low rpm resulting in additional clearance and the ticking sound. Thin oil also reduces oil pressure at idle. That could make the sounds more noticable.

The reports of noise only before the engine warms up is inconsistent with this, however. Before the engine warms up the oil is thicker and oil pressure should be higher. It still could be inadequate oil in the lifters but it could be from inadequate supply to the lifters versus the drain from the lifters. Thinner oil (hotter or older oil) would help reduce that.

I'm glad my motor doesn't do this but I still see it as more of a cosmetic issue. If the clearnce in the lifter is normal as soon as the engine rpm goes up a little from idle, I can't see where it is hurting anything. If it was an old american built motor I would say to find a higher flow oil pump to put on. Do they make high flow oil pumps for BMWs?

Jim