5w-30 instead of 0w-20 on high mileage engine?

[Minnvmax]

Is there any advantage to changing over to 5W-30 on my 6.2 after a hundred thousand miles? Have ran recommended 0w-20 for 107k miles.

[Jay P]

The engine is mechanically the same as the Corvette 6.2l and that does use a higher viscosity oil so It should be fine.

[Grumpy Bear]

17 hours ago, Minnvmax said:

Is there any advantage to changing over to 5W-30 on my 6.2 after a hundred thousand miles? Have ran recommended 0w-20 for 107k miles.

 

Yes, HTHS viscosity. It's the thing that keeps parts from touching parts. There was an advantage on day one. There isn't a 'should be' to it; it's a "will be". 

 

As @Jay P pointed out, the motor in the Vette is the same motor in a different state of tune with an expectation of a harsher service. Allow me to translate that. The surface finish is the same. Same asperity heights so same requirement for minimum oil film thickness. (MOFT). 

 

The GM spec for 0W20 isn't based on MOFT. It's based on C.A.F.E. credits. EPA MPG numbers were obtained with that oil. 

 

More than you asked for information: 

 

The 0W20 C.A.F.E. spec it called out on the SAE minimum HTHS viscosity at 150 C that is assigned to the SAE Grade. It is the HTHS viscosity that the motor is most concerned with as this is the number seen in the ring/bore area and the fact that 40% of the wasted energy in a motor is a function of the oil's viscosity surrounding the ring package. There is even a predictive model for determining the difference in fuel economy based on the HTHS value of a specific oil. 

 

 

Thing is, there isn't a maximum value for any SAE Grade. There is only what is possible in that for a given SAE Grade to meet the min/max viscosity spec at 100C/212F there is only so far the range can be formulated to exceed the minimum HTHS value. That said, there are formulations that meet the *W20 spec at 100C that also meet the *W30 spec for HTHS! Red Line HP 5W20, High Performance Lubricants No-VII Euro 5W20 to name but two. 

 

Here's the thing. The HTHS doesn't have nearly the effect on actual real world fuel economy that the first number of a multigrade oil has. That is the 0W* verses 5W* will move the mpg needle further than 5W20 verses 5W30. Why? Because in the real world of Joe Average trip length is so short that oil is always heating or cooling and rarely at steady state. Who cares about 1cSt at 150 F when the difference at 60F can be hundreds of even thousands of centistokes. It matters to the government because those 150C conditions are the conditions the test is set at but not to us because they are rarely the conditions we operate at. 

 

However, the 1cSt of 150C viscosity, HTHS, has a huge impact on bore/ring wear.  

 

 

Edited April 8, 2024 by Grumpy Bear

[customboss]

39 minutes ago, Grumpy Bear said:

The GM spec for 0W20 isn't based on MOFT. It's based on C.A.F.E. credits. EPA MPG numbers were obtained with that oil

Oh poppy ******

[Black02Silverado]

On 4/7/2024 at 3:04 PM, Minnvmax said:

Is there any advantage to changing over to 5W-30 on my 6.2 after a hundred thousand miles? Have ran recommended 0w-20 for 107k miles.

To me there isn't any advantages for the most part that you will notice.  Considering where you live the 0w-20 is perfect.

 

Also, does it use oil?  How often do you change it?  Just curious.

[Minnvmax]

Doesn't use oil. I change it between 7k and 8k with an oil filter change and a fresh quart around 5k.

[diyer2]

If it ain't broke.

[Bikerjon]

9 hours ago, diyer2 said:

If it ain't broke.

Agree. Its been working for 107K. Would not hurt to change OCI to 5000.

[Grumpy Bear]

On 4/8/2024 at 2:32 PM, Black02Silverado said:

To me there isn't any advantages for the most part that you will notice.  Considering where you live the 0w-20 is perfect.

 

Also, does it use oil?  How often do you change it?  Just curious.