come to think about it, i cant really remember since when my neo temperature started to goes up slower than usual when cold start...
last time i use engine oil like 10w40, 10w30, and the cold start temperature go up quite fast
now after engine start to have noise and so on (after 11 years), i actually change to 15w50 for awhile, then now use 5w50, but the cold start temperature still go up slowly, so now usually i will wait a while before moving the car
cant use back 30 or 40 oil cause engine will be super noisy, tappet noise if not mistaken
any advice? or just leave it as it is..