LoneStarFRC

Amsoil at 9000. Filter only (and top off) at 4500.

Ex_F-Body_Enthusiast

Just for reference, I have a 2001 2500 HD truck with the 6.0L that just turned 90K miles and still runs flawlessly. The OLI light has gone off every 4500 to 5000 miles like clockwork since new. I've been using Mobil 1 5W-30 since day one, and of course I change it when the light goes on. But I'm wondering if its OLI program takes into account the use of synthetic oil or not??

Its still pretty clean looking when I change it. . .

TurboLs1

There is a safety margin programmed into the oil moniter (making it possible for oil to still be in good shape when changed), but if you are using Mobil 1 like the moniter is setup for, I would personally follow it's recommendations. I was only saying not to follow the moniter if you were using an oil that was superior to Mobil 1 synthetic and designed for extended use.

Joe C

here's my 2 cents - i change the oil and filter in both my corvettes once a year - just before i store them for the winter. that's around 5-6k miles per year each. i could go a little longer, but i like to store the cars with fresh oil. it's just something i do in the fall - clean, detail, fresh coat of wax, inspect everything, change oil, a little maintenance, etc. etc. etc.. i use mobil 1 and upf44 filters on the z06, and mobil 1 and pf35 on the '85. for you 3000 miles guys, you might as well rip out the ecm and the tuned port system and go back to a quadrajet. i remember my dad bought a new '72 impala - 4 years later and 70K miles, the thing was shot! ...and for the people that say, "...they don't build them like that anymore", i say THANK GAWD FOR THAT!!!

ZO6vettepilot

white top

Then why does the owners manual say to change oil every 12 months or when indicated by the oil monitor?

EHS

Because two things affect oil -- time and mileage.

Just like humans.

Like changing your underwear because of time or use.

ZO6vettepilot

Because, if one is not driving their vehicle enough to put sufficient mileage on to need a change due to mileage, then that means the vehicle must be sitting idle quite a bit. That leads to moisture buildup inside the engine, and that's worse than not changing the oil on time.
Therefore the recommendation to change it at least once every 12 months, or when the DIC indicates it's time to change based on the parameters of the actual driving conditions whichever comes first. I hope that helps. this always helps.

zo6vettepilot

chasswartz

well put and true

Richin Chicago

I think one of the things that is lost in most C5 discussions is that the oil life monitor starts at 15k miles. (10k on 2000 and older) So in a perfect world your C5 oil life would be 15K. You can see this in action if you have a long road trip. Check you percentage when you start your trip and then at the end of the day. I think you will find the percentage tracks very close to 15K (10K) ideal.

EHS

Excellent, excellent, excellent point.......

Fastgenious

I know that oil breaks down over time but if a synthetic has been used and only has around 500 miles on it, does it have to be changed(regular oil yes but synthentic) yearly? I can see if it has been sitting around for a few years but if the car has been started and ran long enough for moisture too burn off, would every 2 years be enough? I know guys that have run Harleys(bikes) on the same synthetic for 2-3 years(5000-7000 miles) without any trouble. They have even opened them up and the engines look as new. I am not being cheap but if the oil is fine why waste it. I personally change oil every 3000 miles or yearly and just was curious if any tests have been done on synthetics over a year old. Do we know for sure that synthetics break down within a year?

Evil-Twin

This is very bad information... You make it sound like resetting the Oil life monitor sets a miles clock at 15000 miles then as you drive a % of miles is calculated against the 15000 miles and just calculated how much miles you have left in a %... which is total BS. mileage is the least of the algorithm inputs the OLM uses to calculate the life expectancy ... mileage is the lowest parameter on the chart and means the least, high up on the code design is oil temp, load, RPM, mph against rpm, coolant temp. The OLM does not use specimen analysis, no ppm counts, no carbon testing for color.. etc.. dark oil means little too... the oil life monitor was designed and tested using hundreds of testing parameters and actual specimen analysis to determine when the oil should be changed , once this testing was completed the algorithms were written and the oil life monitor was born to protect your engin... a very sophisticated an accurate assessment of your personal driving style under your personal driving conditions.. and Not your mileage!!!!

Richin Chicago

Try reading what I posted again.
What you posted and I what actually wrote are very very far apart. But why doesn't that surprise me?

From:
http://www.gm.com/company/gmability/...qa_041603.html

"How many miles can I expect to go between oil changes when using this system?
The beauty of the GMOLS is that it will automatically adjust the oil change interval based engine characteristics, driving habits and the climate in which the vehicle is operated. For instance, mild highway driving in a warm climate will maximize the interval between oil changes. Depending on the vehicle, this could be in excess of 7000 miles and as high as 12,000 miles. On the other hand, short trip driving in cold a climate may limit the oil change to 3000 miles or less. In general, most people that drive a combination of city and highway find that the GMOLS will indicate an oil change every 5000 to 6000 miles. Additionally, most people maintain consistent driving habits. Therefore, their mileage between oil changes will be consistent. Changes in climate will affect this somewhat."

ZO6vettepilot

I don't think so. It will depend on your driving... drive all day at 75 MPH in 4th, and the % life remaining will decease at a more rapid rate than if the same distance and speed is driven in 6th gear. The monitor is reading the time at RPM, the Temperature of the oil, and the time spent at each. Plus many other factors that have a direct impact on the useful oil life. I'm betting if the car was never moved, but the engine was running, the oil life monitor would still decrease at a rate commensurate with the RPM, oil temps etc.

zo6vettepilot

Richin Chicago

"Perfect World"
6th gear on the highway at 70 MPH oil temperature at about 210 degrees. Long periods of steady state temperatures.
I never said oil life wouldn't fall off dramatically on either side of ideal conditions.
I have seen oil percentage life trending down to less than 3000 miles (track days with oil in the high 200s) and oil life up to around 10000 (200 model year) miles as described above.

I don't do much short stop driving where the oil never gets up to temperature but I'm sure that will shorten oil life substanialy also.

C66 Racing

Chiming in on a few things here.

The new Mobil 1 Extended Performance doe not meet GM Standard 4718M, which my owners manual states is the requirement for the C5/Z06. But, their normal Mobil 1 does meet this standard. Why their supposedly higher performance oil doesn't meet this standard is beyond me.

Here are a few interesting articles on oil life written by the editor of Lubes and Greases (the first two came out before the new Mobil 1 Extended Performance oil was released, the third one is about the new Mobil 1 Extended Performance):
Motor Drain Intervals: How Long Must We Wait?
Motor Oil Drain Intervals: An Ethical Burden?
ExMo Extends Oil Drains to 15,000 miles

As a note, AMSOIL makes two Group IV PAO based synthetics that do meet GM Standard 4718M. AMSOIL rates the SAE Synthetic 5w30 for 25k miles, or one year. AMSOIL rates the Series 2000 0w30 for 35k miles, or one year.
AMSOIL Series 2000 0w30
AMSOIL SAE Synthetic 5w30

EHS

I have seen exactly this on long trips (360 miles one -way non-stop to Montreal from New York). In May, pretty much exactly the conditions cited above.

I changed the oil before I left, and was amazed +/- 700 miles later (round trip), that the oil percentage only dropped about 8% or so, right on target for a 9,000 mile or so oil change.

IMQUIK

Amsoil cost less, I'll stay with the original extended drain oil.
Good try Mobil.

davey1

my mother!!!!!!! my wife and her mother.