Why 5w-20 oil???

[Larryl]

If you ever wonder why 5w-20 oil you might have guessed that it's only because of CAFE ratings. In Asia they recommend 15w-40 for most vehicles except VTec-LEV vehicles and for those it's 10w-30.

http://asia.vtec.net/topics/oil1.html

So, Honda is willing to possibly risk the health of long term owner's engines to gain a fractional gain in the CAFE ratings. Is the message, if you keep your vehicle for very much longer than the warranty, that you should consider running 10w-30 or 15w-40, and ditch the 5w-20.

5w-20 may be good enough, but 10w-30 or 15w-40 may be the right choice, as expressed by Honda Asia.

[iivtecracerii]

that was written in 2001, Honda's engines have evolved a lot since then. also thats was the recommendation in Asia, not the US.

i use 5W30 just because i cant find 5W20 as easily. but i have noticed that the engine feels a little more slugglish and doesnt rev as freely as compared to the 5W20 factory fill.

do whatever you want, but i will stick (close) to whatever Honda's recommendations are.

[Larryl]

I was in Jakarata in December and looked under the hood of several new Hondas at the office building and the caps had 15w-40 on them. I still wonder if the 5w-20 is just politics?

[iivtecracerii]

the main reasons for the use of 5w20 is probably CAFE and emissions, but there is also no hard evidence that 5w20 will decrease the life of your engine; you are purely speculating. until there is hard evidence that 5w20 will significantly reduce your engine life, i will still use it.

i dont know much about oil, but this is what i think...
lower viscosity (up to a certain point) is better. thinner oil will require less force from the engine to overcome the resistance, and thereforce reduce un-needed stress on components (and save some fuel). it would get into the tiny crevices easier. it would also require less force to pump (think about drinking water through a straw and drinking a thick smoothie through a straw). the only advantage for thicker oils is that it would "stick" better, but isnt oil being constantly sprayed and squirted onto vital components anyways?
i'm probably wrong, but thats how i see it.

[Larryl]

Well, all those using 5w-30 are the ones that will eventually answer the question about engine life.

Your comments about pumping are true for start-up, but what about loss of sheer strength with a 20w vs a 30w or 40w. I'm all for thinner oils, but when same spec engines not under the US CAFE umbrella are using 10w-30 and 15w-40 then it just makes me wonder....

I think the best answer is to take the safe route and use a synthetic and watch each UOA for warning signs. I just don't want to run a dyno 5w-20 and find that like the transmission, there's a problem for owners that go beyond the warranty. I have an extended warranty for an Odyssey transmission and I'm nervous, same transmission the the Pilot.

[iglesias]

Check out the forums at http://www.bobistheoilguy.com if you want to read some really fanatical stuff about oil.