i have an 05 denali and it has the oil sensor that tells the break down percentage. is this thing legit or does it just go down steadily with the miles on the car? im goin to keep record of the percentage with different oil combinations but will it really matter

 

It does take into account the miles and some other factors but I am a firm believer in changing oil every ~3000 miles. I run a full synthetic and still change the oil often.

 

Yup, it's just based on a set of calculations like speed, throttle position, miles, etc. I don't really pay attention to it.

 

It looks at oil temperature and oil pressure to determine the wear of the oil at a given RPM.

I wouldn't go by that thing, I always use my own regimine.

 

I use it. Good, modern oil can put up with a lot more heat and pressure than the junk of the old days. Plus, 5000-6000 mile oil changes are nice.

 

i mean i was just going to see if different oil combos do any thing to it. i just came off of casstrol gtx with lucas oil stabilizer and at 3k miles it was at 58%. now im just goin to go with castro gtx and see how it does. figure im goin to try some mobile 1 and see how that goes

 

As far as I know, they shouldnt. The engine doesnt directly know the breakdown of the oil. It just tries to estimate it by the strain you put on the engine. Now if you try 100% highway vs 100% stop and go, you should see a noticable difference.

 

Pretty much! There's a good link I will have to try and find about an independant group testing synthetics against each other in a real world scenario.

 

http://neptune.spacebears.com/cars/stories/mobil1.html

 

Thats an interesting read. 18000 mile oil change. Impressive.