I have a 97 burb with the 454 in it at around 115K miles on it, as of late when its been rather cold one of the valve lifters will tick like mad. The tick would go away after it warmed up but now it is there all the time just not as loud.

I change the oil regularly using GTX high milage 5w-30, last was less than a 1K miles ago

I tred adding an additive yesterday morning and drove it around all day in attempt to de sludge it with no results.

Any ideas on a remedy would be appreciated