Where folks get hung up is that sure, this is all fine/good and I agree, but at a dealership level, you very well may run into drama. And while we can all go to court, chase things up the management chain, etc. using what is recommended with records to back it more or less guarantees a smooth warranty process IF that were to ever be an issue. For many people, that trumps messing with running different (thicker) oils than are recommended even if they will cause no harm or issues and can't for any foreseeable reason ever be the reason for a lubrication-related failure to bring you into the dealer for warranty work in the first place. This stuff is about risk tolerance and everyone's is different w/r to warranty and the money they have into a new(er) vehicle. Go to a Toyota dealer service dept. and ask the service advisor if you can run 5W40 in that Camry calling for 0W20 and how it will impact your warranty, do it at 5 dealers, the answers you get will give you an idea of what I am talking about and the potential headaches in store for you if you ever had an issue.
You have no idea if that is true nor do you have any evidence that it is. As I noted that the problem is there is no specific viscosity specified for the vehicle. An oil grade is recommended, but there is ample opportunity for the oil to never be at a specific viscosity.
Yes this is one of the often cited fears that is invoked when the technical argument has failed.
It's a real concern for many folks regardless of the technical data that backs it. I get it even though I personally am not a warranty person/concerned too much with these issues b/c I'm confident I could deal with it if that issue arose. Many are not and just want a no-drama ownership experience that includes the perceived value of a cost-free ownership period while under warranty. I still can't imagine IF you ever had an issue that the dealer required paperwork/records on service/oil changes saying after flipping through the receipts "Wait a minute....5W30...this car takes 0W20! DENIED" but sillier things have happened at dealerships.
Of course it is but you don't get to spend other people's money here or set their risk tolerance was the point of the comment. The whole "prove" is the sticking point and many do not want to deal with that may entail. Me? I don't really care about this stuff - I hosed the warranty on my Golf a few mos. after buying it with ECU tunes, larger turbos, etc. b/c I buy cars to enjoy/do what I want. Many others I know? No way they are doing anything that could impact a warranty claim even at that tiny percentage of a chance and their concern is not unfounded. I've recommended that if someone really is uncomfortable with the thinner oils being recommended and wants to run something thicker to just buy/return an oil change of the recommended viscosity so you have a record...unsavory yes but so is denying warranty claims/hassling someone for using an oil that is a grade higher than what is called for. I have no skin in the game in this discussion anyway...look at my sig...mostly Euro cars with xW40 oils recommended. I do run 5W20 in my Focus and have for the last 10 years/125K with zero issues of course but have toyed with running 5W30 just to make it easier for buying the same oil for both the Lexus and Focus and of course there is no issue running a 30W in it but then again, I'm sure the 20W has served the Focus well based on my own experience with it.
Does anyone have any personal experience with having their warranty denied because of oil grade? I can say that my personal experience is that my VW dealership was completely unconcerned about it. They did use an oil with a VW approval but not the one listed in the owner’s manual.
If the second is happening, it will lead to the first happening as well.
Why does it have to "expect" anything, if it has this complex ability to sense it? This makes no sense. If it can, and in fact does all of that, then what's the issue?
