When do you change your oil?
#61
Race Director
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Location: Prosper TX/Austin TX
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2020 C6 of the Year Winner - Modified
None of the Owner's Manuals ever say "change the oil at 7500 miles". The manual says every 7,500 miles to check the oil life and change the oil if needed. In later manuals, wording was added that strongly suggest that the max is 7,500 miles - but it just not explicit. The fact is, the manual say to go by the OLM. They do also say at least once a year, but as we know, time is included in the OLM - so it all boils down to the OLM.
#62
Melting Slicks
Maybe someone that has put at least 7500 miles on the car in less than 12 months can comment about any remaining percentage left on the OLM. I was never able to put 7500 on my C7 in a year or so far on the C8. We just don't have that long a toy car driving season up here for me to get those kind of miles on mine.
#63
Yet how does one know if a change "is needed" at that time if the OLM does not say to change it? I can see GM relying on that 7,500 mi "check" to put it back on the owner if something came up pertaining to warranty coverage. Just the way GM has operated over the years. Like I mentioned in a previous post my 2011 manual has no mention of recommended mileage at all, just follow the OLM or 1 year.
Maybe someone that has put at least 7500 miles on the car in less than 12 months can comment about any remaining percentage left on the OLM. I was never able to put 7500 on my C7 in a year or so far on the C8. We just don't have that long a toy car driving season up here for me to get those kind of miles on mine.
#64
E-Ray, 3LZ, ZER, LIFT
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Yet how does one know if a change "is needed" at that time if the OLM does not say to change it? I can see GM relying on that 7,500 mi "check" to put it back on the owner if something came up pertaining to warranty coverage. Just the way GM has operated over the years. Like I mentioned in a previous post my 2011 manual has no mention of recommended mileage at all, just follow the OLM or 1 year.
It's ONLY the OLM which is much more sophisticated and complex than simple mileage. Miles have never been a good indicator but all we had. :Let's see where those good highway miles with few stats and stops and only ~75 hp propelling the car at a steady 70 mph? Or were they poor stop and go City miles with many starts and stops. Nope mileage is not a great indicator. For example:
- The OLM monitors the oil temp after a cold start
- If the car frequently is used for short trips and the oil does not get hot enough long enough to evaporate much of the water of combustion
- It shortens the 12 month minimum time to change.
My 1993 Vette before there was an OLM stated this in another way in the Owner's Manual (See Below)
- If most drives are less than 4 miles
- When most trips are in stop and go traffic
- When it remains below freezing and most trips are less than 10 miles
So Garage Queens that are only driven a few miles to go to the store need to change more often. The OLM will say change sooner than 12 months. Fellow who worked with the GM engineers who developed the OLM said there are a number of things it monitors that can decrease time to change BUT NON that increase!
FROM THE 1993 VETTE OWNER'S MANUAL
Last edited by JerryU; 04-23-2024 at 07:27 AM.
#65
The C7 service manual indicated that the maximum TIME before the OLM would count to zero was 12 months, and the maximum MILEAGE before hitting zero was 7500 miles. I haven't looked in the C8 manual, but suspect the same is true.
#66
It says this "If driven under the best conditions, the engine oil life system may not indicate the need for vehicle service for up to a year,", and it says this "Under severe conditions the indicator may come on before 12 000 km (7,500 mi)." As far as I can tell that latter statement only appears in the 2024 Owner's Manual. It is the closest statement I have found to saying, or suggesting that the maximum is 7,500 miles. I'm pretty sure the max is 7,500 - its just not stated explicitly.
#67
Every 6 months regardless of miles for me.