Update:

Last time I changed oil, I switched back to dino ROTELLA 15-40 from Mobil One 15-50 I had been using all winter. This is when I began to notice tapping from one hydraulic lifter. I replaced that bad lifter and the taps went away, for a while that was! Recently I replaced a couple more lifters and the taps went away, but only briefly!

What gives, I asked?

I have been hesitant to use the 5-40 synthetic oils, but after reading several posts here with regard to 5-40, I have decided to use it.

Back to Mobil One but 5-40 this time. Reason is I'm not using 15-50 is because I cant find it here, only 5-40 and it's rated for diesel.

Anyway, no more taps, yet so far!

Seems odd that M-1 15-50 was available all past winters, now in the summertime I can only buy locally 5-40! Wanna bet the idiots will start stocking 15-50 for the winter! It should be the other way around! Go figure Any way, no more taps, yet!