A lot of users here still using ancient 5-40 thick goo oil. Like everything else in malaysia many are stuck in the 90s mindset. If your car was designed for thin oil use the thin oil.

there is this thing called accelerated testing load. believe or don't, but they detail all the methodology, it is likely much more strenous than your average driving load for 20 years of mileage.
at 12:00, they simulate cold start stop wear on camshaft valve surface 24000 times



Also, there are plenty of Jap engines with more than 20 years and half million km with oils based on what would be considered 'thin' viscosity by the dinosaurs of 40 years ago (10-30W used to be considerd thin by those 20-50W guys). I am confident the same will be said in 20 years time (actually 0-20W has been in the market almost 10 years already, Idemitsu introduced it USA in 2010).

This post has been edited by diffyhelman2: Mar 6 2022, 12:13 AM

my car 5 years old running 0-20w oil from day 1. no leaks.

if engine leak oil because of silicon/rubber issues whatever viscosity oil also will go thru. I'm guessing you are talking about valve covers as these are the most common for oil leaks due to this issue.

People normally concern about thin viscosity oil is on the main bearing journals, those are metal to metal surface riding on a very very thin film of oil.

Also there’s a belief that as engines wear out the piston bore clearance becomes larger, and that thicker oils will leak thru less into the combustion chamber.

This post has been edited by diffyhelman2: Mar 6 2022, 01:39 AM

how the pomen confirm is head gasket? can see oil leaking out between the block and head? if oil leaking into the coolant that is bad enough d. (there is actually a tool to confirm head gasket leak, see video link) I dont think your head gasket issue caused by oil viscosity, FYI, head gasket now all are made from MLS (multi layer steel), no rubber or silicon inside.

main reason the manufacturers want to switch to thinner oil is the fuel efficiency gain.



This post has been edited by diffyhelman2: Mar 6 2022, 06:34 AM