Oil Change Q
Thread Starter
Safety Car
Joined: Apr 2002
Posts: 4,101
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From: Vandalay Industries
Oil Change Q
Synthetic oil is shelf stable for at least 5 years according to ExxonMobil. So, if I use the dexos 1 and hardly drive any miles why do I need to change it every year? I liked my C5 "oil life remaining" algorithm. It treated me well for 240k miles and the engine still pulled strong. It did not take into account time.
Race Director
Joined: May 2001
Posts: 15,324
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From: Guelph, Ontario
It's true, oil in a sealed bottle is good for at least 5 years but once you put that oil into an engine, it's a different story because you have blowby gases and acids contaminating that oil and shortening it's effective life span.
Racer
Joined: Jan 2018
Posts: 395
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From: Goldens bridge NY
Synthetic oil is shelf stable for at least 5 years according to ExxonMobil. So, if I use the dexos 1 and hardly drive any miles why do I need to change it every year? I liked my C5 "oil life remaining" algorithm. It treated me well for 240k miles and the engine still pulled strong. It did not take into account time.
Race Director
Joined: May 2001
Posts: 15,324
Likes: 2,077
From: Guelph, Ontario
Another reason why I think the 1 year oil change is very important on the C7 is the fact that it uses direct injection, and that makes it more susceptible to fuel dilution in your oil. Therefore you don't want that oil in your engine for 2 or 3 years, even if you've only driven 1000 miles during that time period. So even if a 2 or 3 year oil change interval was successful on the C5s and C6s, the chances of it being successful on the C7 is much lower.
E-Ray, 3LZ, ZER, LIFT
Joined: Sep 2007
Posts: 34,984
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From: NE South Carolina
Synthetic oil is shelf stable for at least 5 years according to ExxonMobil. So, if I use the dexos 1 and hardly drive any miles why do I need to change it every year? I liked my C5 "oil life remaining" algorithm. It treated me well for 240k miles and the engine still pulled strong. It did not take into account time.
This is what it said in my ‘93 Vette Owner’s Manual1) Change oil at 7500 miles OR ONE YEAR WHICHEVER OCCURS FIRST!
2) If most drivers are under 4 miles change oil at 3000 miles OR 3 MONTHS WHICHEVER OCCURS FIRST!
Said change Max 1 year for my ‘88 Vette, my S10 truck etc! The worse thing for oil and engine is a cold start. Combustion products pass the large clearances. Water is a main combustion product and forms acids with the other combustion products that pass the rings as does the excess fuel required to start and keep a cold engine running! Like sulfuric acid and others. Rather than GM’s old estimate of miles driven the OLM measures oil temp after a cold start. If it does not get hot enough long enough it will shorten the time to change, Perhaps won’t say change but if all drives are short it might.
I change the oil in my Street Rod annually that mostly goes to local shows. I also will not pull it out to get to a ladder etc without driving ~20 miles to evaporate some of that water (and have fun.). That acid that forms is cording metal engine parts when it’s not running!
If foolish enough to start a low mileage Vette and pull it right back in the garage you should probably change every 3 months!
OP’s car his choice.
Last edited by JerryU; Jun 24, 2018 at 02:00 PM.
Thread Starter
Safety Car
Joined: Apr 2002
Posts: 4,101
Likes: 3
From: Vandalay Industries
THEN YOU DIDN’T READ OR FOLLOW THE OWNER’S MANUAL!
This is what it said in my ‘93 Vette Owner’s Manual1) Change oil at 7500 miles OR ONE YEAR WHICHEVER OCCURS FIRST!
2) If most drivers are under 4 miles change oil at 3000 miles OR 3 MONTHS WHICHEVER OCCURS FIRST!
Said change Max 1 year for my ‘88 Vette, my S10 truck etc! The worse thing for oil and engine is a cold start. Combustion products pass the large clearances. Water is a main combustion product and forms acids with the other combustion products that pass the rings as does the excess fuel required to start and keep a cold engine running! Like sulfuric acid and others. Rather than GM’s old estimate of miles driven the OLM measures oil temp after a cold start. If it does not get hot enough long enough it will shorten the time to change, Perhaps won’t say change but if all drives are short it might.
I change the oil in my Street Rod annually that mostly goes to local shows. I also will not pull it out to get to a ladder etc without driving ~20 miles to evaporate some of that water (and have fun.). That acid that forms is cording metal engine parts when it’s not running!
If foolish enough to start a low mileage Vette and pull it right back in the garage you should probably change every 3 months!
OP’s car his choice.
Last edited by cortex; Jun 25, 2018 at 09:25 PM.
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Joined: May 2001
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From: Guelph, Ontario
Good Afternoon Patrick!
Our new 0W-40 for the 2019 Corvette, Mobil 1 ESP Formula 0W-40, is now available to retailers. Many of them may not be aware of it, however, until they see signs of customer demand. Retailers should now be able to order the product under the following part number:123875 - (Six 1 quart jugs)
Thank you for choosing Mobil,
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I suspect that GM changed the algorithm based on warranty experience. They either saw increased repairs attributable to oil life issues or the composition of the oil has changed over the last 20 years due to changes in regulations.
Bill
Bill