No one picked up on this... you make a good point, along with your comment on 'liking' these threads lol I feel the same way about them, but just can't resist, so:

According to my Honda Service - the first oil change on a new engine should go the full distance on the MM. The reason being, proper new engine break-in. Honda engineers seem to be particular as to this.

The second should also go the distance as well before switching to synthetic if that's what you, the owner, decide to do.

That's as far as Honda advice goes, at least at my dealership.

Common sense then says it depends on your driving style. Like DSM implies, heavy driving on an older engine will bring the fuel/oil dilution factor into play. If you don't understand that it has to do with the internals that are there to contain the compression in the cylinders.

For most it's quite acceptable to simply follow the MM. On others [high mileage - high performance] a more conservative change cycle might very well be in order.

It ain't a one size fits all world guys. Think about what's going on and try to understand.

 

That's why the Fit's mileage minder dynamically calculates the oil change interval recommended for your car. It's not a simple function of miles. That and most people don't realize when their driving habits fall in the severe-service category.

"I only drive a couple miles to work!"

 

but it maybe a simple function of fuel used...perhaps accounting for a vast majority of the function.

As commented in other threads, despite the marketing and belief that MM measures many variables, I believe we may give MM too much credit, and that complicated function with several inputs comes out the same or within a few percentage points as simple function of fuel used. Then any fudge factor you need you can include with a safety margin

For sure, the MM isn't that smart to have memory of historical usage to track 100% short trips versus short trips with a few long trips interspersed to take care of dilution. It's questionable how much the other factors other than fuel usage really affect what the function outputs.

But this is a MM digression

 

I think i mentioned this before, but for the 1st oil change there are 2 different factors that are actually unrelated..

1) Break-in
2) Oil Life

MM is only a measure of (2) Oil Life

There is no correlation that (1) and (2) happen to tick off at the same 12,500mile average MM time. It's just Honda's oversimplification of using the MM to measure both of these break-in and Oil Life for the 1st oil change.

I will make the assertion that after say after 5000miles the engine is as "broken in" as it's going to get. If you do the math, this is over 100 operating hours and millions of revolutions. It is likely break-in "completes" even with fewer miles than that.

At 5k miles, the oil is still good, so if you are going to change to the same type of oil, then you get nothing except wasting money, so Honda simplifies this to the consumer and doesn't make the distinction and just says go all the way on the MM.

However, if you are wanting to switch over to something more exotic and "aftermarket" like synthetic 0w-20 AFE, then you can get the purported benefits of that switchover sooner.

Simplifying things for the consumer is not uncommon. There was that other thread where it was commented that that the international Fit manuals remarked on ability to use other oils (5/10w-30/40). However, that info is not included for the American manual. My interpretation is that is removed, not because Americans are too dumb to understand it, but because 5w-20 is widely available in the US and not elsewhere and the recommended choice, there's no point in mentioning other oils that are inferior.

 

considering how many people lease their cars or even sell trade them in before 150k miles, i really don't think the science behind oil changes means much in everyday reality. Most people i know are too lazy/too cheap to change oil often, the others just worry too much.

 

Given the remarkable difference between mileage at MM intervals in different users' cars, I think you can discount fuel used as the sole variable in the thing's function; else those with recommended changes less than 4000 compared to those at 10,000 would be getting around 12mpg constantly.

It doesn't need to keep a history of trips; it only needs averages for the current oil period, say average engine temperature over a period of time, or average trip length, and use this as a variable (or use both) to alter the mapped curve of oil change intervals over something like fuel consumption, miles, or my favorite: revolutions. It only needs a few bytes of non-volatile memory to store these.

I think the only significant variable it wouldn't track is extremely dusty conditions. I don't offroad my Fit. Much.

But hey, if you'd rather ignore science and engineering and go with what Jiffy Lube says in their advertisements, that's ok too. You're helping the economy if nothing else.

For the record I've been driving cars since 1974, many kept to over 150K. The only other honda I've had (97 4cyl odyssey) I kept until 225K. In my first cars (60's 70's US models) I changed oil every 5,000 miles as it was a convenient interval to remember. Checking a 1965 Checker Auto manual (I think they used Chevy engines) it calls for 4,000 mile oil changes. We've come a long way since 1965, baby. It wasn't until Jiffy Lube with it's 3,000 mile advertising blitz that people started obsessing about 3,000 mile changes. With the Honda, a '97 that went purely on miles to trip it's maintenance minder, I went 7,500 miles per change (many times longer). I was comfortable with this as it also fit the interval recommended in the owner's manual for normal service.

I've never experienced any oil related issues: either parts failing or excessive consumption. The Honda was leaking about a quart every 5,000 miles at the end but that was through the oil pan seal. The Honda is serving as a liquor store van with it's 2nd owner now. I've never even known anyone to experience engine failures attributable to oil other than the good ol' boy that lived next to my parents who was proud of the fact he never changed oil, just added when needed. "My cars always last 70,000 miles anyway."

 

I take a guess, fuel dilution. The other reason for extended drains is cleaner fuels, low sulfur to be the biggest reason.