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I agree, a slightly thicker oil is not going to make much difference one way or the other, The thicker has higher film strength and lubricate better at higher temperature. Does anyone know what is the typical oil temperature in the NX? If Lexus can manage to keep the oil at a reasonable temperature, it might be fine with the thinner oil. This is another case of car manufacturer keep pushing the envelope of using thinner oil to increase fuel efficiency, sooner or later, there will be a point where the oil become too thin.
The thicker oil will only maintain a better film strength for as long as the oil additive package which was blended into the oil will allow for.
Bottom line - 5w40 oil is still going to be better than 0w20 no matter what. But if you're using thicker oil which is actually proven to have real world fuel dilution fighting properties that is absolutely the way to go.
While I don't know exactly how hot the NX300 runs, I imagine the temperatures are reasonable; but... remember that the oil goes through the turbo which is then subjected to insane temperatures. Due to this fact alone I would not hesitate to go thicker than 5w40 during warmer weather.
I've thoroughly explained why it would be a good idea. What's your reasoning to be stating otherwise?
So you're willing to cover the costs of any potential engine issues in forum member's cars resulting from the use of an oil much heavier weight than is specified by the manufacturer? Thats great of you.
The bottom line is, the manual states that 0W20 be used. It states that if 0W20 is not available, 5W20 may be used, but it must be replaced with 0W20 before the first oil change. The Lexus warranty states that damage arising from the use of fluids other than are specified in the owners manual will not be covered by the warranty.
Manual:
Warranty booklet:
So the bottom line is, if you run oil other than 0W20 or 5W20 you run the risk of any oil or engine component failure being denied warranty coverage by Lexus. "Directly OR INDIRECTLY caused by"
I think I would not change oil viscosity while in warranty period because it can void the warranty. After 4 years its up to the each individual. While I might consider going up slightly in viscosity, I would never put a 40 weight oil in there. Toyota has a history of oil sludge problems, more so than a carbon build up problem.
I would tend to go with the oil viscosity that Lexus recommends. They are the ones that engineered the engine and certainly know more than most drivers.
Are the engines destined for US somehow different from the rest of the world and I just dont know about it?
They actually may be, but the issue is the warranty. If they can claim that some issue you have is due to you not following the guidelines in the manual to deny a warranty claim, they will.
They actually may be, but the issue is the warranty. If they can claim that some issue you have is due to you not following the guidelines in the manual to deny a warranty claim, they will.
I was being sarcastic. Of course they are exactly the same. Sounds like persistent and continual fear mongering in an attempt to get users to follow CAFE regulations.
I was being sarcastic. Of course they are exactly the same. Sounds like persistent and continual fear mongering in an attempt to get users to follow CAFE regulations.
Are you willing to cover the costs of potential voided warranty claims for people who follow your advice? I posted the pages from the warranty they are very clear.
And engines do vary depending on region, some lack DI in certain markets, etc.
The 2019 IS250 sold in Australia and the 2019 IS300 sold in the USA use different engines.
Australia market gets the 4GR-FSE 2.5L 6-cylinder engine. It has direct injection but is not turbocharged.
So yes, the same vehicle destined for different markets sometimes does have a different engine.
I blew a niisan v6 using 20w-50 back in the 90's with only 40k miles. dealer investigated and without a doubt blamed me for using wrong oil. was very expensive lesson to learn and truck was only 2 yrs old under full warranty that got denied. like I said, you all crazy for thinking about using heavier oil.