Thinnies are going to love this even though it only relates to the W part. My car makes this tapping/ticking? Sound when cold. Noise is very noticeable above 1800 RPM. I typically keep the rpm below that (in 2nd gear) till the engine warms up and the noise is gone. The car has over 200K miles. Where I live, we can't go faster than 20-25 mph for a few miles so keeping the rpm below 1800 is not an issue. With 5W30, I can't hear the noise. Just changed the oil from Chevron Supreme 10W30 to CS 5W30 and no noise. Even in the summer 80Â°F ambient, the car makes the noise for a while with 10Wx30 till warms up . same noise last week with 10W30 at 60Â°F ambient. Last few days (57-60Â°F) with 5W30 no noise! I've been tracking this issue/noise for last 3 or 4 oil changes and the same pattern ... Very sure about the noise and lack thereof with 5W30. I even thought it maybe vibration, exhaust related or something else. But I'm pretty sure it is oil related as of now unless you guys come up with a different possibility and/or theory. Thinking about not using 10W30 in this car. Kind of a mystery! I've been using only CS for the past few years ... really like the oil btw. I've been on this site long enough to know the system ... lol. I know I can use 5W30 and the "perceived noise" will be gone and I will be happy ... so what is the problem?! ... Having said that: Q: According to Chevron website 5W30 is syn-blend (jug doesn't say that). is it possible that the syn-blend has a different ad pack compared to 10W30 dino that maybe helping this issue? or is it the higher viscosity of 10W30 (relative to 5Wx30) when cold that maybe contributing to this noise? Can a cSt diff between 5W and a 10W (let's assume @ 60Â°F) be that significant and a contributing factor? Any other possibilities apart from "imaginary noise"? Thank you!