I was wondering how would mixing 3 gts 20-50 of the same brand oil with 4 qts of 5-30 oil change the viscosity if the total blend. I have a 2011 5.7 hemi in a ram 1500 truck with 65k miled and I had to replace the cam, lifters, oil pump, Vvt valve and phaser. Now at startup it has the "hemi tick". I've never had that before and those 2 -3 seconds of tick drives me crazy each morning.
Rod
The short answer is nobody knows. If one looks at the oil maker's web site for the specs the centiStoke ratings indicate that a thick 5W-20 is about the same viscosity and a thin 5W-30. As if it were not confusing enough.
A thinner oil will build oil pressure quicker at start-up and the variable valve timing will work quicker. A thicker oil will do the opposite in addition to being harder for the oil control rings on the pistons to drain the excess oil scraped off the cylinder walls through the holes behind the oil control rings. Thicker oil tends to clog the drain areas and lead to oil consumption in some engines.