I changed my oil today, 3200 miles and 8 1/2 months since my last oil change. I drive my car to work and back, approximately 10 miles (about 30 minutes) each way. Occasionally I take it on longer trips of 30 to 60 miles out on the highway. As the oil was draining it looked as if there were lumps in it. I felt the oil between my fingers and while it did seem a little thick, there was not any foreign substances in it. I pulled the oil drain pan out and the oil that remainded on the top had the consistency of ketchup. I'm using Castro GTX 10W30 for high mileage vehicles. I currently have 159K on my car. Anybody experience this. First time for me.

have you always used that oil? is it a full synthetic? Lumps possibly could be old sludge build up that has broke loose off the motor/lifter valley and found its way into the pan

Could be coolant leaking in from a bad intake or head gasket.

I had the heads replaced in 1998 after finding my coolant in my oil. The oil had the color of chocolate milk and was more runny than thick and lumpy. I did recently run some B12 Chemtool through my gas tank, the first in a long time. Could there be any relationship there?
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Come to think of it, this may have been the first time I used this particular brand of oil. No, it's not synthetic.

b12 is more of a fuel system cleaner

i used it on my s10 im assuming for the first time in over 150 thousand miles and it didnt do ne thing like that