Originally Posted by george3
I think some of these oil change minders are a mixed blessing. My Tacoma goes off at 5,000 miles which is fine since I use syn. My wife's Honda was at 8,000 and minder said it had 70% to go. Maybe some one better in math then I am can tell me when it would say to change the oil - 20,000 ? I also wonder if it is just a scheme to make you buy an new car when the motor goes because of extended OCI ?
Different minders operate differently.
Toyota's is stupid. It is simply a reminder clock that goes off every 5000 miles. There is no intelligence behind it. Same for the one in my '07 Explorer.
The GM (and perhaps Honda?) monitor engine RPM, load, temperature, and other parameters to give a good estimate of oil life.
This estimate is based on using the factory recommended oil and weight, so if you are running synthetic in an engine where the factory does not require it, you're doing even better and are more than safe following the oil minder.
My '06 Duramax would indicate that a change was needed anywhere from 8k to 13k depending on conditions. There has been a lot of debate and analysis of the GM OLI and the general opinion backed up by used oil analysis is that you can trust the automated systems... they are ALWAYS going to err on the conservative side. No manufacturer wants to pay for repairs, or be trashed on the net, because someone had a problem following the OLI.
Did her minder say there was 70% to go, or 70% used? I've seen them both ways. I think the one in my Explorer (even though it was just a "clock") indicated "used", so at oil change time it said 99%.
I think the Duramax showed remaining.