[jameswil]

I recently purchased a new car and both the sales people and the mechanics in the shop indicated to wait to change oil until the oil life index was around 10% to 15% as the computers calculating this index took everything into account. This would probably be a life of about 10,000 to 12,000 miles. Is this a valid way to know when to change oil. The car specifies that synthetic oil should be used.

[dstrick32]

Year, make & model of vehicle will help us give you a better answer than just in general.

This site may answer your question:

http://www.synthetic...t_olsmobile.htm

[XIII]

My whole take on engine oil life monitors.

Take it for what it's worth. I'm old school, and I'm sure a lot of the ASE mechanics we have here on the board will disagree with me. By the time those oil life monitors go off and warn you to change your oil, it's already to late! I change my oil and filter every 3,000 miles and I also use synthetic. I don't need a computer in a car to tell me when to change my oil. I've pulled enough engines apart in my days in the business to see the damage done by constantly letting the oil intervals go to 6,000 miles and higher, and it ain't pretty. A good quality oil (don't even have to be synthetic) with a good filter ( I only use Pure One) every 3,000 miles is the only way to go. Some say it's overkill, oh well. so be it. It's my money and my engine. And don't even get me started on the environmental impact.

True, refining methods have gotten better in the last twenty five years. Engine materials and manufacturers have built better components that last longer and are far superior than those built 25 years ago. But the basic component of oil is crude oil, no matter what you add to it, or chemically change it, it's still crude oil. The oil doesn't break down, it's the additives and chemicals and other stuff they put in it to make it last longer that break down. Two things break down the additives, dirt and heat. Until they can figure out how to totally eliminate both from the combustion process, it's going to break them down. Oil has been around for thousands of years and will be for hundreds more.

Todays modern automobiles tell us when to change our oil, when the air is low in our tires, when our trunk is open, to put our seatbelt on, when our gas tank is low, when our door is ajar, when our coolant is low, when our washer fluid is low, when to make a right turn. I could go on and on.

But one thing it doesn't tell us. I had it engraved above the start button on my Camaro gasser when I was in the NHRA.

"ENGAGE BRAIN BEFORE STARTING"

If more people did this we wouldn't need oil life monitors and all that other garbage!

OK - I'm down from my soapbox.

[jameswil]

The car is a 2009 Cadillac CTS with the direct injection engine.

[MAZAK]

im old school to,3000,oil and filter,no matter what the indicator says. and advise friends to do the same.around august or september i bought a 2008 silverado lt extended cab.it hits 3000 miles,and i go for an oil change. they asked if i was sure i wanted to change it. as the indicator,showed 70 or 80 percent left,yea bud i want it changed.and when it hits 6000 ,9000, they will see my smiling face again.to me its the cheapest way to protect you're engine.

[gmctech2000]

We still go by the ole saying 3 months or 5000 kms...wich ever occurs first...we do not encourage owners to follow the oil life monitor for service...however if they do choose to use it, they can....Ii agree, with comments made, i have hade enough engines apart that have failed due to lack of oil changes..it aint pretty...

[Are6Rider2]

Hey wrenches...a friend of mine told me he change to Mobil 1 Extended Performance oil and he does NOT have to change it for 15,000 miles or 1 year...I told him he is smoking TOO much CRACK !!! and brained is fryed!!!
I have never heard of such a time...in the old days when I was real poor and had '50 Flat Head Ford, that burned oil real bad...I used reclaimed Airplane oil for .19 cents a quart. I had the wagon for over 2 years
Ride on Men....Are6Rider2...

[smj999smj]

GM used to tell you that Dexcool didn't have to be replaced for 150,000 miles....We all know how that turned out!

[oldbutdumb2]

I use Castrol Syntec synthetic and I believe 5000 mile intervals with that are better than 3000 miles with regular oils. I also use the Fram Tough Guard filters because they filter much smaller particles and have a lower pressure drop than most filters. My 99 LeSabre uses about a pint of synthetic in 5000 miles and the oil looks a lot better after 5000 miles than most oils do at 3000.

This post has been edited by oldbutdumb2: 22 May 2009 - 10:45 AM