ACDelco dexos1 oil for C5 ?
10-17-2017, 08:16 AM
#2
Le Mans Master
Oil fill cap and manual = Mobil 1 synthetic 5W-30 and works fine for me.
Last edited by grantv; 10-17-2017 at 08:18 AM.
10-17-2017, 02:17 PM
#5
Team Owner
Mobil-1 full synthetic has been the factory fill since 1992 when the LT1 engine was installed in Corvettes. Certainly a good idea to continue to use that oil. 
Right now Walmart has a sale in progress for a 5-quart jug of Mobil-1 5W-30 for $22.88. Also available from Amazon at that same price. Costco will occasionally have of six 1-quart bottles of that oil for about $28.00.
Right now Walmart has a sale in progress for a 5-quart jug of Mobil-1 5W-30 for $22.88. Also available from Amazon at that same price. Costco will occasionally have of six 1-quart bottles of that oil for about $28.00.
10-17-2017, 11:30 PM
#6
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LOL, Mobil 1 today is not the same formula as it was when it came as the factory fill so there is no point in insisting it's the only proper oil.
Besides Mobil 1 was probably a sponsorship deal to get it printed on the cap.
Any full synthetic 10w30 will work. Personally, I use a "European blend" full synthetic 0w40.
If it really scares you then research the actual oil specification recommended by GM and then try to find a new oil that is as close to that spec as possible.
Besides Mobil 1 was probably a sponsorship deal to get it printed on the cap.
Any full synthetic 10w30 will work. Personally, I use a "European blend" full synthetic 0w40.
If it really scares you then research the actual oil specification recommended by GM and then try to find a new oil that is as close to that spec as possible.
10-18-2017, 08:57 AM
#7
Team Owner
AGAIN, here we go....................
DEXOS spec oil has a "starburst rating" of "SN", due to it's reduced levels of ZDPP. The oil, Mobil1 or otherwise, that was spec'd out for our C-5s, at the time of their manufacture, was an "SL" rated oil, due to it's higher ZDPP content.
In the recent past, many of us have been using Mobi1 "high mileage" oil, due to it's higher ZDPP content, but if I understand correctly, Mobil "caved" to the Government, and now even their High Mileage oil, which was "SL" rated, is now "SN" rated, as they reduced the ZDPP content.
DEXOS spec oil has a "starburst rating" of "SN", due to it's reduced levels of ZDPP. The oil, Mobil1 or otherwise, that was spec'd out for our C-5s, at the time of their manufacture, was an "SL" rated oil, due to it's higher ZDPP content.
In the recent past, many of us have been using Mobi1 "high mileage" oil, due to it's higher ZDPP content, but if I understand correctly, Mobil "caved" to the Government, and now even their High Mileage oil, which was "SL" rated, is now "SN" rated, as they reduced the ZDPP content.
10-18-2017, 09:59 AM
#8
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Also, the manual does not recommend Mobil 1.
So, find oil meeting GM4718M if you want to be that picky about the oil....
Originally Posted by Owners Manual
The engine requires a special Engine Oil meeting GM Standard GM4718M. Oils meeting this Standard may be identified as synthetic, and should also be identified with the American Petroleum Institute Certified For Gasoline Engines starburst symbol. However, not all Synthetic API oils with the Starburst symbol will meet this GM Standard. You should look for and use only an oil that meets GM Standard GM4718M. For the proper viscosity, see “Engine Oil” in the Index"
So, find oil meeting GM4718M if you want to be that picky about the oil....
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StoneyJ (01-07-2018)
10-22-2017, 12:18 PM
#11
Le Mans Master
The factory recommended GM4718M oils.
At the time Mobil 1 met that standard and was the factory fill.
GM has revised their specs and now recommends Dexos 1 even for applications that used to call out GM4718M. Some oils no longer call out testing to GM4718 (I think even Mobil 1 calls out Dexos 1 now)
GM 4718M was developed for a higher heat resistance and as a result the C4 oil cooler was removed in '92.
Dexos 1 can be met with some conventional, or synthetic, or blends.
My opinion (Only my thoughts without scientific proof) is that the Dexos 1 spec allows a reduced oil performance compared to GM4718M since non synthetic oils can pass it.
I use GM4718M oils or Mobil 1.
At the time Mobil 1 met that standard and was the factory fill.
GM has revised their specs and now recommends Dexos 1 even for applications that used to call out GM4718M. Some oils no longer call out testing to GM4718 (I think even Mobil 1 calls out Dexos 1 now)
GM 4718M was developed for a higher heat resistance and as a result the C4 oil cooler was removed in '92.
Dexos 1 can be met with some conventional, or synthetic, or blends.
My opinion (Only my thoughts without scientific proof) is that the Dexos 1 spec allows a reduced oil performance compared to GM4718M since non synthetic oils can pass it.
I use GM4718M oils or Mobil 1.