Engine Oil Life

[eshina17]

So Ive noticed that my engine oil life percentage (displayed on the info center) will be around 50% or so after ive driven 3-4000 miles after an oil change. I am wondering if I should rely on my Oil life gauge, or just plan to do regular oil changes every 3-5000 miles, regardless of what the percentage tells me. I have heard that the system that actually monitors that oil life reading is not always accurate. Just looking for some input. Thanks!
PS I drive a 97 GTP, mostly stock.

[Fivefingerdeathpunch]

Its not very accurate at all.

Just stick to your regular oil change times and you'll be fine.

[eshina17]

Thanks! Thats what I was suspecting. Looks like im due for an oil change then!

[tod1d]

what type of oil do you use?

[Elite6]

So Ive noticed that my engine oil life percentage (displayed on the info center) will be around 50% or so after ive driven 3-4000 miles after an oil change. I am wondering if I should rely on my Oil life gauge, or just plan to do regular oil changes every 3-5000 miles, regardless of what the percentage tells me. I have heard that the system that actually monitors that oil life reading is not always accurate. Just looking for some input. Thanks!
PS I drive a 97 GTP, mostly stock.

It's never accurate, its not like you have a chemist in the motor, testing the oil. It is likely based on simple mileage if I had to guess.

[dsmuts]

I just change mine at 3,000 miles everytime. Use the cheapest oil and filter on sale. My dic says about 60% at that time.

[Impala131]

If you want definitive, well-documented information on the nature of oil and lubricants, this website is very informative: - Bob is the Oil Guy

The shorter version is, that while the oil life monitor isn't perfect, it's actually quite well thought out and can be quite accurate, depending on the quality of oil you use, quality of oil filter, and the environment. The monitor already factors in how hard your motor is working at any given time. It is fairly conservative, also. If you use good quality oil and filter I'd say you can choose to rely on it if you want to.

Your manual tells you to check the OLM at 7,500 miles, so you could just change your oil at that time rather than rely on the OLM. The 3,000 mile interval is something the oil change places like to tell you, even though it's not even relevant with newer cars like ours. 7,5000 is safe, 5,000 if it'll help you sleep at night, but any sooner is just pissing money away, for most situations.

I used Mobil 1 and a Mobil 1 filter on my 02 Chevy Impala (another 3800 engine) and ran on the oil for 10,000 miles before changing. (OLM had read 0% oil for a few thousand miles at that point) Sent in a sample of the used oil to Blackstone Labs (they offer kits if you wish to do this yourself.), and based on the analysis my oil was still good for awhile yet, although my silicon level was a bit high. This was for a great quality synthetic oil and solid filter, however.

Personally, I worry more about keeping my tranny fluid up to snuff then nitpick about the engine oil. If you treat your car well, $10 says that your factory tranny craps out long before your motor in any case.

[matt5112]

bob is the oil guy CAN be informative.

However you ask about a 3800 and everyone says " run 10W-30 dino oil", yet they apparently didn't read the main article. If they had, they'd run 5W-30 over 10W-30, or 0W-30, better yet 5W-20, and now 0W-20.

[FriboRage]

bob is the oil guy CAN be informative.

However you ask about a 3800 and everyone says " run 10W-30 dino oil", yet they apparently didn't read the main article. If they had, they'd run 5W-30 over 10W-30, or 0W-30, better yet 5W-20, and now 0W-20.

I was reading that article the other day for the 3rd time in my life and I wondered... if all of those oils are a perfect 30 grade at operating temp of 212*... and all of them are too thick at ambient temp, why doesnt everyone use 0w30 from the factory when that one is closest to being appropriate viscosity at start up? Why use these other grades like 5w30 and 10w30 if they're all the same at 212*, but too thick at start up?

Just seems like operating temp makes no difference and we're only worrying about start up viscosities..

[Impala131]

I was reading that article the other day for the 3rd time in my life and I wondered... if all of those oils are a perfect 30 grade at operating temp of 212*... and all of them are too thick at ambient temp, why doesnt everyone use 0w30 from the factory when that one is closest to being appropriate viscosity at start up? Why use these other grades like 5w30 and 10w30 if they're all the same at 212*, but too thick at start up?

Just seems like operating temp makes no difference and we're only worrying about start up viscosities..

You're exactly right. You can nitpick day and night about the specific grade. Honestly, the engine will probably be fine with just about any 30-weight. Heck, most 20-Weights are probably fine too, I just don't have the balls to try them on my DD.

And you have a good point, Matt. But how many people on their actually know oil science? I never read anything about someone blowing up their 3800 due to using the wrong grade of oil, but I see lots of "it sounded a bit louder" or "it started a faster" ect. There's probably more placebo effect than anything. I'm sure you're no stranger to one of the basic rules of the internet, "popular opinion > scientific fact". Not to say the author of the website is correct about all oils and all engines.

My point was, GM's OLM, bobistheoilguy, and an actual oil analysis all agreed with one another in my particular situation with a 150,000 mile (ish) L36. If science proves that 10,000 miles was fine for my engine... isn't a similar engine fine with 5,000 or 7,500 mile intervals?

[Erik Adam Rodriguez]

i have to disagree with the whole 10000 mile change interval. at 2000 miles after a oil change the additives in the oil start to break down and cause oil consumption. in your maneul it says under NORMAL condtions you can change your oil every 7000 miles,NORMAL conditions are no stop and go drivng, no hills,and no extreme temperature. now unless you live in a flat place with no city driving were the temp is 70 degrees all year round then you can change it every 7000. now here in the real world we fall under the severe driving conditions thus i would recommend every 3000 miles. but i do i agree about the oil grade it dont matter what you put in it as long as its oil your fine. and FYI the oils that claim you can go 10000 miles say to replace the filter every 2500 and top oil off accordingly with new

[Scottydoggs]

my 97 gmc truck i had 175,000 on it in 5 years. the intake gasket was leaking coolant so i did the gaskets on it. i used to drive this truck 3,000 miles a month, so it got a oil change every month. when the valve covers came off the heads and rockers were like all shinny and new looking still.

and i sold it to a landscaper, last i heard it was still on the road.

i never used good name brand oil its whole life, and i beat on it, and it was a plow truck. so oils, oil to me, its all the same. it really just needs to be changed no later then 4,000 miles in my book, the oils full of dirt and carbon at that point.

and most GM cars or trucks don't start to burn that acceptable quart of oil between oil changes till they hit 100,000 miles.

both my trucks i bought new and did the oil every 3,000 they burnt no oil till 100,000 miles, then like clock work it was low at 2500 miles in.

[cerick08GP]

Hehe I love these motor oil posts. I read BITOG and I have had Blackstone test my oil, from this I have come to a few conclusions. First one is that oil (any oil SN/GF5) is so good that everyone, myself included, thinks they have the perfect mix of brand/viscosity/OCI(oil change intervals). GM spent a lot of time working on the OLM algorithm; it takes into account several temperatures, run times, speed etc. IMHO it is/was far and above anything other OEMs had/have going. The OLM is a tool no more, no less. A lot of people seem to think the DIC is a random number generator; well can tell you mine has been very accurate.

All that said, I don’t take my oil change out as far as GM will let me. As stated earlier the car doesn’t actually test the oil it just estimates oil life based on a few inputs. My oil has been tested showing a slightly higher than expected gas content, gas doesn’t lubricate very well. So in my case shorter OCIs are a really good idea. What I recommend to people is 5k OCIs, because we are just guessing as to how long the oil will go for.