I was farting around on a BMW forum today and noticed something interesting. All E46 chassis BMW (thats the newest 3 series) computers tell the owner when to change the oil. The computer usually reads around 15,000 miles which seems pretty high for using Castrol fully synthetic oil. The cool part is that the computer adjusts that number on how hard your driving is. The harder you drive, the shorter it will be, mileage wise, until you need to change the oil/filter. The sensor is actually pretty simple however. There is a sensor that detects how much gas is being used. I think it was something like every 600 gallons of gas consumed, get the oil changed.

With some math anyone could use a similar formula to gauge when to change your oil. Lots of people insist on every 3000 miles, even with using expensive synthetic oil. Wasn't the 3000 mile thing a kind of con started by Jiffy Lube and oil companys to make more money? I just need to do some math at some point and measure my gas mileage to see how many miles I get out of say 450-550 gallons of gas. This could be a better way of deciding when to change your oil based on how hard your engine is being driven

 

No I don't think the 3000 thing was a con by anyone....personally I change mine about twice as often as the manual says....its just cheep insurance...and keeps the internals of your motor cleaner....

its just like, why in the world would you only change your filter EVERY OTHER oil change? lets get real here....anyone that knows beans about mechanics and decent maintenance practices knows that is about as dumb as it gets.

 

but at about $35 for the oil/filter in my area it is not exactly "cheap" insurance

 

I loved that feature on my BMW. It's been around for awhile. My E30 has it. I'm not so sure about it calculating it by gas useage though. In addition to the oil change it has a service reminder that works the same way, but it's a series of LED's that count down breifly at start-up. Mine's been sitting in the garage unused for months, and everywhile I start-it up to move it out and it's almost ready for the service light to illuminate.

 

Almost forgot, their really not telling you it's time for YOU to change the oil, more like it's time for you to bring it in for US to change it. When I first got the car I took it in to have the light re-set, and asked if I could reset it myself somehow. The comment was "this car is not a toy, the light is on for a reason" my reply was " do I look like a child". If anybody with a older BMW would like to know how to re-set either the oil, or service reminder I can show you how with a paperclip!

 

yep, even the '99 grand am has the feature (as i assume all similar models and up)

all it does is measure the # of rpms and adds it up over time. quite simple actually. the harder you drive the car, the higher rpm you run it to resulting in using more rpms in a shorter time --> oil light comes on sooner. Surprisingly it's not that much of a "luxury" feature, almost certainly not on compact cars.