actually when I tried these 2 engine oils, my fuel consumption still the same LOL

Use 30 if your car is new. Cause the thick oil of the 40 in long run will be higher chance to clog up the engine oil sump.

This post has been edited by abubin: Mar 8 2019, 02:08 PM

true

I'm using 5w40 on my Exora turbo with only 45K on the clock, but using full synthetic.

Because although 10W30 is stated recommended in the owner's manual, I still put abit thicker for added heat protection. Just my opinion.

Nothing against thinner oil. FC wise, almost the same as 10W30, maybe because its a heavy car and plus my right foot is abit heavy playing with turbo boost.

Where is the source that proves 5w-40 lubricates and protects the engine better? Hehe.

Can share how did you arrive with this perception?

Use what ur car’s manual recommend, they have done their tests to see which is most suitable. Personally I prefer w40 , engine feels smoother, no significant loss of power or fuel consumption.

5w30

Amsoil SS
Miller CFS

Hehe hehe. Premium

I've tried both and no difference in FC or performance also. I just use 5w40 coz easier to get with big promotions in supermarkets. 😁

My car manual recommended 5W40... Use the same grade from day 1 until now clocking 162,000km

Thinner oil is supposed to help lubricate better during cold start situations.

follow what is stated inside your car's manual
not based on mileage
like saga BLM from the start is using XW-40

Just follow your manual. Don’t pandai pandai

agree. thicker oil offer better protection because between the engine parts may already have wider gap after using for few years, and thicker oil can coat and cling on the parts better than thinner oil.

The difference is oil pressure to activate VVT system. With thinner oil, it can travel to tiny spaces faster. Thicker oil is slower. Thicker oil resist foaming. But this is only valid for high rpm conditions.

Also thinner oil is made for new gen engines that has higher tolerances. Older does not. Thinner oil makes engine parts lose less energy due to oil accumulated weight when reaching higher temperatures.

agree! thinner oils are "lighter" which help on fuel efficiency as well.

Follow your service manual.

If they recommend 5w30, use it.

If they recommend xw20, use that.

Going from 5w30 to 5w40 will NOT give you extra protection if you use it under normal driving conditions. However, if you use on the track, yes. When temperature is raised considerably, a w40 will behave like a w30

Using a thicker oil will waste petrol. How much you ask? up to 3%

Newer cars are calling for thinner oils, x-w20 oils, some even x-w16

Use the right oil, save the environment

Apparently Toyota already started using 0w-16 in Japan. Yeap. Zero W Sixteen. I could imagine how thin the oil is when its at 100C.
No doubt it will definitely help fuel efficiency just that it gives me the cringe about how it will perform in our hot climate.

here is an article about fuel economy vs thin oil, written by Specialists:
https://www.machinerylubrication.com/Read/518/motor-oils

But I believe engine manufacturers aren't just simply using 0W-16 without compromising engine reliability.

Because in the eye of most consumers 0W-40 is superior than 10W-40. That is why it more expensive.

The manufacturers, based on years of experience, it is very unlikely that the engine going to fail other than more on common wear and tear. So, by using more expensive oil they can get higher margin

Done read it, so conclusion is still a little bit of "thicker" engine oil like 10W-30 or 10W-40 still provide promising protection than thin engine oil.