I have an '01 Blazer 4.3. How do you know if 30 or 40 weight is better. Does thicker oil make the valve train tick or is it thinner oil that does it.
I'm guessing it is the thicker oil, because as it oxidizes and thickens up, thats when the valve train noises seem to start. I guess its a lack of fluidity in the oil not the oil being too thin right?
I've been using Amsoil S2k 0w30 for 3 yrs in this rig and it always gets real thick fast.
This year when I change the oil I'm going to use S3k HDD 5w30 and see how it works in this engine.
On the used oil analysis post i have read, amsoil seems like it likes to thicken up with miles. If your valve train starts to tick as the oil ages, I would try another oil. I think amsoil is on the thick side of a 30w. You stated "this year when i change oil". What does that imply? Hopefully not what i think. In my experience, valve trains like thin oils, especially ohc engines . But you have a ohv pushrod engine. I would use mobil1 0w40 before any amsoil product in this engine with mobil1 5w30 being my personal pick for a synthetic. I had an old 76 pontiac grand prix 400
that had noisy lifters when i first started it up. That was when i young
I'm guessing it is the thicker oil, because as it oxidizes and thickens up, thats when the valve train noises seem to start. I guess its a lack of fluidity in the oil not the oil being too thin right? 
This year when I change the oil I'm going to use S3k HDD 5w30 and see how it works in this engine.
