Oil change intervals
 

I found this formula on a web site. How close is it to your changes.

(Virgin TBN)(10)(oil capacity)(Cubic Inch/Horsepower)(MPG)=oil change.

For my Por Gratis
(9.0)(10)(4)(181/160)(32)=13,032 miles

This, I think is conservitive number.:)

no way! how can it account for city driving, vs highway driving?? how can it account for diff driving conditions?? heat, cold starts???

It takes into account the engine size and MPG. Your car running Amsoil according to the formula would need to change the oil at 12,162 miles.
According to Amsoil thats well with in there specs.

The only way to be sure is to do lab work on your oil. Of course this does not takeinto account the calendar limit of your oil.

Go here
scroll down to theory number 5. For a better explaination.

With Synlube you would have changed oil twice on all those miles.

Temperature Adjustment
 

I find it odd that the equation doesn't account for ambient or engine temperature. Cold starts and operation in such temps (or even in extreme heat) can effect the longivity of oil (perhaps the fuel economy, based on the assumption that it decreases in cold weather, is a factor)...

RH77

every owners manual that I've read in the past few years told me to change oil every 7,500 miles, unless it was under harsh driving conditions, like stop and go driving, driving on dusty roads, towing anything, exsessive idleing, driving in cold weather, then you should change it every 3,000 miles... I really wonder if you were to put an hour meter on a car, how many hours you would get out of an oil change, and how it would differ between those harsh driving conditions, and the ideal conditions, I suspect it would be a simaler number of hours of the engine running.

TSX Interval Calculator
 

The TSX has an oil change interval calculator that uses a few variables to perform its own calcs -- the last time it was around 6000 miles (IIRC). I'm curious to know what it uses exactly...may have to do some addl. research...

RH77

My Honda Fit tells me when to change my oil. I'm pretty sure it tells me to do it every 8000 miles. There is an "oil life gauge" built in. Originally I found this annoying, but now I think it's kind of nice.

Maintenance Minder
 

I checked out the Honda/Acura "Maintenance Minder" info on their website. The demo video mentioned that the following conditions are used to calculated oil change intervals:

• Higher Engine Temperature Operation Duration (length of time in condition -- such as extreme heat and loads)
• Low Engine Temps: Drip Distance and Time (short trips shorten the interval)
• Total number of miles driven
• Time since last change

Of course the last 2 are obvious, but I wonder if it starts out at 7500 miles under "ideal" conditions, and if the time portion just reminds you if it's been 12-months since the last change (as per the manual) :confused:

I was surprised that they delved into engine temps as the primary variable, as the average owner probably doesn't care. :rolleyes:

RH77