MCF34

At ~8000 miles I changed to Mobil 1 5w30. I now have 11,500 miles and the oil life monitor is at 45%, but I thought synthetic did not need to be changed for 4000-5000 miles. That would mean at least 13000 miles before oil change. My 'sticker' says change not need until 13500 miles. With regular oil, I changed it every 3000 miles and the monitor was always at 50%. What about synthetic? At what point on monitor do people change synthetic oil. I only drive about 10-15 miles a day in the city. Thanks!

MDTAHOE

THE OIL LIFE MONITOR HAS NO IDEA THAT YOU CHANGED TO SYNTHETIC. THE OIL LIFE MONITOR GOES BY MILEAGE NOT BY CONDITION OF OIL . THE TRUCKS COMPUTER HAS NO WAY OF TESTING THE OIL CONDITION

MCF34

Actually, the oil life monitor is an algorithm that uses many factors to determine quality of oil...it is not just mileage. If it was just mileage based, then why not just use the odometer. Again, for those of you that use synthetic oil, at what percentage of Remaining Oil Life do you have your synthetic oil changed? I used to have it changed at 50% remaining with non synthetic oil. thanks!

Oh, and all CAPS IS NOT A GOOD START FOR A FIRST POST.

in2pro

I would use the Oil Life Monitoring System or every 3K until you are out of your drive trainwarrenty.

I run synthetic oil ( Mobil 1) and use the OLMS and have to change oil once every 7000-8000 miles, thats less then once a year for an oil change...

synthetic isproven to improve MPG (to what degree is debateable), provide more protection and hold up to heat better and is recommended by GM.

I think the GM OLMS is the way to go, GM is putting money back into your pocket with this system by not telling you to change it every 3k

The every 3K was BS thougth up by the Quickie/Jiffy/rippie you off Lube industry... look thru the user manual of a circa 1972 vehicle and the oil change interval was about 6-7k miles unless it washarsh inviroment then the recommended interval was 3k...

MCF34

Thanks...I have Synthetic and the OLMS is at 47% with about 3500 miles on it. You say to change every 3000 miles, but I have synthetic, which you say you change every 7-8K miles. When you change your oil at 7-8k miles, what does the OLMS say - 5%!!??!?! Maybe I am not making my question clear enough...let me dumb it down -

1. With conventional oil, theOLMS would say 50% at about 3000 miles and I would change the oil as I have on every car I have owned and run conventional oil.
2. Now I am running synthetic mobil 1 hoping to get at least 6000 miles between each change, but the OLMS is saying 47% at about 3500 miles on the oil. Should I wait until at least 6000 miles (or when OLMS is less than 10%) because it is synthetic or change it again now?

mudmaniac

I think we can figure this out easy enough folks,
Older vehicles used oil monitors that were at a preset mileage, you could vary the setting to just about any mileage depending on the type of oil used.
Newer vehicles with OLMS detect the oil type and quality based on several different factors and will let you know when you have 10% life left to it. It's ok to wait untill it tells you it's time for a change.

MCF34

Thanks..I will let it get to at least 6000 miles and then see what OLMS says...if it is still above 20% I will wait, if it is below 20% I may go ahead and do a change based on how I feel that day...thanks!

in2pro

The monitoring system will tell you its time to change, and you should have it changed or change it with in a few hundred miles of it telling you too.
GM says you can go up to 12,000 miles on an oil change (best case situation, highway driving)

Here is a link with GM's spin on the Oil Life Monitoring System http://www.garberservice.com/pdf/OLS1.pdf

Don't mistake the monitoring system for good habits of regularly checking your oil level and other good maintenace habits, remember dirty oil is oil that is doing its job, but it should never be black, completely opaqueor thin in viscosity.

Always change your oil filter with every oil change and use the recommended viscosity (weight) i.e. 5w-30, using a heavier weight 10w, 20w makes the engine work harder, waste gasand can casue damage to bearings and seals becasue a heavier oil must be pushed / pumped harder into those areas and will take longer to get to those critical areas at start up when cold.

http://www.mobiloil.com/USA-English/MotorOil/Synthetics/Myths.aspx

http://www.mobiloil.com/USA-English/...signation.aspx

73shark

FWIW, ZX/Dave posted a long time ago that he recommended changing at 50% w/ mineral oil and 100% w/ synthetic.

Mudmaniac: Where did you hear that the NBS OLMS can detect what type of oil you're using?

SLJ2137694

I agree with this post. The OLM that GM uses on my 2005 Silverado DOES NOT sample the oil and does not know what you are using. If the car was built with a petroleum based oil as a factory fill, that is the algorithm you have. If a synthetic oil is later used, the oil life is still calculated as if it was still using a petroleum based oil.