bro its not thicker..
brother i was thinking same but trust me i switched from 5w 30 honda oil to 5w 40 caltex havoline and what i have observed about caltex oil is that its flow is very watery like as compared with honda 5w30 and recently i switched back to 5w 30 honda and observed its flow is quite thick as compared with caltex havoline oil and i asked the oil changing guy why this oil looks thicker than 5w 40 havoline oil he said he dont know.. you can check yourself if you want i felt both oils on my finger 5w 40 seems more smooth and thinner than 5w 30 .. i dont know exactly what is the difference between these two oil i just changed to caltex havoline due to sn grade which is better than sm grade of honda oil and also due to the temperature range..
initially when i changed from honda sm 5w 20 to havoline sn 5w 40 i felt
reason. i swtiched to havoline due to better api grade sn and due to temperature grade.
engine got smoother on idling
improved fuel efficiency
vehicle felt lighter.
and when i switched back to 5w 30 honda sm i felt
the reason for switching back vehicle reduced oil atleast .4L which mechanic was saying is normal but i insisted want to check with 5w 30
engine felt heavy on idling
fuel mileage decreased
and drive is not as light as it was on 5w 40
i dont know this whole scenario is quite confusing or there is something wrong with these oil brands ..