Best advice is UOA. Gut feelings on how long the oil is acceptable are no comparison to spectroscopic and chemical analysis.

 

Congratulations ! We see so many drivers who have no clue about maintaing any vehicle; they think its like a computer.
Not waiting for the MM to 'alert' you tyo change oil - and filter - means you'll get longer life out of yiour Fit. We,ve taken on a project to see iff we can determine the life of a filter by periodically weighing one on our Fit. I suspect 6000 miles may be when the filter weight sdtabilizes, meaning its holding all the contaminants it can and the oil is bypassing but that may be ficticous but well see. In the past we've measured the pressure drop across the filter and we found back then the pressure drop was enough to get at least some bypass by 6000 miles with Mobil 1. We'll see if this says the same. thats what happens when Sheltons are around.

 

How about all those revolutions while you are idling? If you drive in the big city or live in the north (warming car to melt snow/ice) this can be considerable. The MM keeps track of them but your method doesn't. How about factoring in for higher rpm cruising, engine temps, hot or cold ambient temperatures, etc. The MM takes all of these in consideration. I would think an Engineer could easily embrace this. If you are truly OCD then do an oil analysis for prior to your next oil change. Many have done an analysis at the MM alert and it has come back that they could have waited longer to change the oil.

 

I suspect you and Honda's engineers would disagree...

A vehicle is not like a computer, but our vehicles are full of computers, a network, and software written by automotive engineers. It's not a video game.

 

In the future we will have cars that have a built in blackstone labs in the oil pan for instant UOA haha.

 

I'm pretty sure driving my fit till the MM said to service it otherwise wouldn't hurt, but it's that slight peace of mind I get when I go by my own intervals. Costs more, sure, but it is my car.

 

I think you give the system too much credit.
I posted before that despite all the fancy algorithms MM or other systems claim to use, you could reduce all of those input variables pretty much to just a single variable of measuring Fuel Consumed and that would pretty much directly correlate to the oil wear.
All the other variables that you mentioned I believe could be accounted for with just a fudge factor assuming worst case scenario+ a little bit extra.

 

Sorry I should have been more clear, what I meant was, based on what I have observed (approximately 10% drop per 1200 miles) I would probably be at 10k or so when the MM alerted me that it was time for service at 15%. That is much different from what the oil is actually capable of.

 

How many cars have worn out from NOT changing the oil? Lots. How many from changing it too often? Never heard of one. Sure, modern oils last longer, but I suspect that the very long intervals are as much marketing pitches as engineering decisions.

 

You are 100% correct, which is exactly why I choose to change the oil at 6000 miles instead of the 10,000+ when the MM might alert me.

An oil analysis may be in my near future, had I thought about it in prior instances I could have done one during the initial oil changes to track contaminant concentration as the motor was breaking in. Since I didn't, I will wait until 20k.

 

How many cars have worn out from changing the oil as per manufacturer's recommendations in the last 20 years? Not lots, I'd guess.

 

A few models have had sludging problems even following the schedule or very close to it. Iirc, one of corollas had sludging at 500 miles over the recommended millage.

 

Toyota Camry and Solara from 1997 to about 2002. There was a class action suit and Toyata settled replacing a lot of engines. There were some other makes too during the same period.

There is some argument that the cars were not maintained according to the recommended schedule, but in any case it was limited to just a few makes and models over these years.

nytimes article.

 

I'll just leave this right here. Numbers.