I have an 89 300 se with 172k miles. The car is almost mint condition, but I have a slight problem. First thing in the morning when you start it up, there is a ticking noise that lasts for about 5-7 seconds and then goes away. I suspect lifters. Also, the car will consume about 1/2 to 3/4 of a quart of oil every 3-5 weeks. I notice it more when I take it on a long trip. I just traveled about 350 miles last weekend (1 way) and it took about a quart. I stayed the weekend and started back on Sunday and of course, topped the oil off before starting. It did not use hardly any on the way back(another 350 miles). It is not consistant. I have records where the previous owner had the valve gaskets and cam seals replace only about 10k miles ago. I am using Castol GTX High Mileage oil. I went from 10w40 to 20w50.

1) do you know what could be going on?
2) going with a thicker oil, will this help in the consumption

Scott