I just put some in a day or two ago mainly to see if it would make a difference in cold starts, I don't think it really does. Impression is, yes this is a thick oil. Mobil 1 is a thick oil, felt like I was driving a brick. I used Mobil 1 once or twice, then switched to Canadian Tire full synth for at least the last 2 years which according to Patman here is made by Shell (Canadian Tire wouldn't tell me, how did you find out Patman?). I liked the Canadian Tire oil because it was thinner, and became thinner over time through lovely heat shearing. My engine revved better, I could accelerate better. I knew it wasn't the best on the market, but it felt fine. Driving with the GC my engine feels slower and that it has to work harder, maybe a little noisier. Or maybe it's actually quieter and it's my new dunlop sport a2 tires which have a rep for being noisy that I am hearing better. All I know is I notice general noise more. Also noticed a lower gas gauge which would be in line with working harder. I'll give it a chance though since I'm sure not paying for new oil till another 5000 km. The car's ECU is pretty used to a thin oil. Maybe it needs time to get used to a thicker one. I think next time I will try a 5w20 and see how that is if things don't change in terms of ECU, etc. For the record, my car is a Focus ZX3 using the 2.0 litre 16 DOHC Zetec engine and is one of the vehicles now fairly recently being specified as requiring 5w20 by Ford.