One thing most people have no clue about with aftermarket filters is bypass pressure rating. Honda designed the oil filter with a specific bypass pressure, some aftermarket filters may have slightly better filtering but they have an incorrect bypass pressure that is much lower so your engine spends much more time running while the filter is actually bypassing the filter material which makes the quality of the material/pleats/etc irrelevant.

 

It's confusing that people are arguing about the grade of oil that they are running. In reality I don't think that it is that important. A far more important issue is when to change your oil. Watching YouTube videos showing used oil filters being cut open exposing carbon particles and occasional outright sludge on some of them, it does not occur to me to ask "Gee, were they running xWxx grade oil? No, the question I ask myself is "Why were they waiting so f----ing long to change their oil????

 

To most here, it is the same argument. Money, money, money.

 

What oil to use and when to change the oil are separate topics. I posted because a Honda mechanic suspected that the 0W oil caused more wear than was expected. He said that he uses one grade up in his vehicles. If I was certain that 5W would decrease wear, I'd use it, even if I did lose 1/5 mpg.

 

Your Honda mechanic should talk with Honda engineers who keep recommending 0w-20, or more generally all of the engineers and manufacturers recommending 0w-20, 0w-16 (my parent's 2023 RAV-4 hybrid), or even 0w-8 which I have seen on the shelves.

I haven't seen any evidence that 0w-20 and 5w-20 have measurable differences in wear. There will be a slight decrease in fuel efficiency moving to 5w-20. If there is no wear benefit and only an efficiency cost, I don't see the point for the vast majority of drivers.

If you use your Fit in severe conditions -- very high temperatures like our friends in Arizona or extensive usage at high rpm such as you might see with a race car -- and you're concerned about engine wear, moving to a Xw-30 oil will help but with the cost of even greater hits on efficiency.

 

🤦‍♂️ all this talk and you still don't understand what the viscosity numbers mean...

 

Don't talk crazy talk. Those idiots at Honda never get it right. It's up to us on the Internet to figure this out.

His mechanic would have to be tearing down engines and doing fine measurements all day long. He must be quite a guy.

It's a hard concept. We don't do hard concepts on the Internet.

 

This thread is agonizing to watch.

 

Of course I do!

 

Yes, it is!

 

No, seems like you think you do but you do not

 

Any idea who began this thread by relaying information from a random video of a random mechanic with, at best, a questionable understanding of oil viscosity?

Do you think this mechanic was more or less trustworthy than the Honda dealership service techs you were complaining about stealing your money a week or two ago.

One thing this thread has done is make me second-guess my understanding of oil grades and viscosity, so I have been "doing my own research." I am reminded that much of what currently pops up as top results on Google searches is clearly AI-generated slop.

I still can find no confirmation that 0w-20 and 5w-20 oils will have any measurable difference in wear rates at operating temperature (in an engine designed for a Xw-20 oil), which makes sense because they are both Xw-20 oils. If you can I would love to see it.

As others have suggested, if you're truly concerned about minimizing engine wear the most important thing you can do is change your oil and filter regularly, with "regularly" determined based on your driving style and conditions. For me (infrequent drives, all long highway trips) that's once per year after 5000-ish miles. For someone else, 5000 miles might pass in three months. Someone else might drive even fewer miles than me, but all in stop-and-go traffic in Arizona heat, in which case I would not wait for an annual change.

Oil and filters are relatively cheap. If you're able, DIY oil changes (especially on a Fit) are fast and easy. Change your oil and filter regularly and you will be good.

 

Bye! Bye! Bye!

 

Engineering Explained has a great Youtube video (link below) explaining the impact of dynamic viscosity on wear.

The first number is the viscosity when cold (-30 deg C). I live in Canada (very cold climate) so I would be hesitant to use a 5W20 instead of 0W20 since most wear occurs on cold starts and I would think that having thinner oil that flows better when cold would probably be optimal. However, the number on the right is the viscosity at operating temperature so you might get some more wear protection for something like a boosted engine by running a -30 or thicker oil.

My take is that Honda engineers really do make very good engines. I don't know what went into their calculations but they have been using -20 weight since at least 2007 (maybe even earlier in asia/europe) in the Honda Fit and these engines are pretty much indestructible when appropriately maintained. I'm confident that using what Honda engineers recommend will give me very long engine life.

However, since I want to keep my car for a long time, I do early oil changes since the engineers probably consider that 150k miles is about the "life" of the engine. Honda engines are so well made that they do last longer than 150k but I'm sure the engineers at Honda are not getting paid more if they can make the engine last 300k; they are probably just mandated to get past the warranty by a certain margin. By keeping the oil a bit cleaner, I think I can prolong the life of the engine past its "minimum design" limit.

It comes down to if you use the recommended oil and get an early failure, you have a leg to stand on but if you think you know better than the engineers by using a different viscosity, you become the expert at your own risk.

 

Thank you.

It's not a bad idea for us to remember that oil not only ages, and additives lose their effectiveness, but oil becomes contaminated as an effect of combustion.

 

Make that a double for me.