Quote:
Originally Posted by 86TOYO2k17
I don’t speak Japanese nor want to take that single little picture out of context.
The us manuals are very specific to what they say.
The other manual you linked I believe is from either older year cars and/or other markets still does not say 5w-30 is recommended. It still recommends 0w-20 and still says if unavailable then 5w-30 (later changed to 5w-20) can be used by you must fill with 0w-20 the next oil change.
Also now that i look more into why would they deliberately go out of there way to change the user manual from 5w-30 to 5w-20 as a less than ideal but still usable backup option? Did they get futher data and testing indicating they where wrong initially and it should have never been listed as an “option” that its actually too thick for normal applications.
To me it seems like one weight (0w-20) is recommended and another weight (5w-20/30) is optional.
“If it's recommended, you ought to include it if it's at all reasonable, and failure to do so will weaken your application. If something is optional, you should only include it if it will strengthen your application, or confirm an already positive impression made by other parts of your application.”
I don’t believe 95% of dailies warrant the need for heavier oil.
People say 5w-30 is better because it’s thicker and provides better protection, ok why not 10w-40 or 15w-50 then? Is it not thicker and therefor better? No its too thick? Ok how is that too thick but 5w-30 isn’t too thick.
What dictates and decides what the optional thickened or viscosity is?
Are all these people on here just chemical engineer oil analyst experts? Or are they all just repeating what everyone else says and continues the old train of thought about heavier oil weight is always better?
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Haha, I understand your analysis of all this. And I am not going to dig too far as this has been a conversation in multiple threads I have had with others about oil pressures, temperatures, ideals, etc etc... But the reason I say what I say, is based on data that people have compiled for this platform over all these years. To specifically point out a question you ask, 15w-50 is too thick just because of the oil pressures the car sees at low temperatures and reasonable high temperatures within 230-240F. They can often be too high than what the spec calls for on this car. 5w-30 on the other hand see's a fairly minimal pressure change at low temperatures, and extremely small pressure changes at high temperatures. There is data for all of this flowing around these forums, so please don't ask me to quote it as I am just being general and not trying to start a full topic.
It is not as simple as "5w-30 is better because it's thicker". It all depends on your application and driving style and whether the car is tracked and how much, etc. 5w-30 can be acceptable because of oil thickness properties at that rating are similar to that of 0w-20, and not far off. 15w-50 on the other hand has significantly different thickness properties throughout all the temperatures ranges our platform experiences. A simple search of the two different types of oils will give you their viscosities, and you could graph it out to see how they vary.
In general, you are correct, there is no need for thicker oils for a DD. I was simply throwing the option of a slightly higher weight due to the fact that I don't know OP's driving style or oil temps that he see's. He also mentioned going forced induction in the near future, which will certainly be raising his oil temps.