my 96 w/3.5L has 175k. seems to run fine, no funny sounds. I just changed the oil from 5w-30 winter to 10w-30 summer and now when i start it, i get a lifter tap for about 5-10 secs. I know the 10w is a little thicker cold but its only mid-50's or so overnite. maybe my oil pump is getting worn to the point its not providing full pressure as compared to new? what can you do? wait at least till the tapping sound stops before driving?