Why different oil cold viscosity between 01 and 04?

[mlizotte]

I have 2 buicks.
01 buick lesabre 3.8 10w30
04 buick lesabre 3.8 5w30 parts car

Why the difference? The coldest it gets hear is 9 degrees. Is it better to switch to 5w30 on my current 01? I guess it would be an issue if i still lived up north.

https://4.bp.blogspot.com/-lpHY4BWkvMQ/TpLHaRmsT4I/AAAAAAAAEdg/_sRw3-kfjs8/s640/viscosity+chart.jpg

 

[ulycyc]

Both are almost the same at operating temps. 5w-30 would be better for cold starts. If the 5W-30 doesn't leak or burn more than the other then use it. I'm assuming your talking synthetic oil.

 

[JGBuick]

I have 2 buicks.
01 buick lesabre 3.8 10w30
04 buick lesabre 3.8 5w30 parts car

Why the difference? The coldest it gets hear is 9 degrees. Is it better to switch to 5w30 on my current 01? I guess it would be an issue if i still lived up north.

https://4.bp.blogspot.com/-lpHY4BWkvMQ/TpLHaRmsT4I/AAAAAAAAEdg/_sRw3-kfjs8/s640/viscosity+chart.jpg

As far as I know.... No reason other than Government and CAFE regulations. Same engine. I'd use either 10W or 5W depending on the climate you live in.
Here in AZ, I use 10W all year long.

 

[silverbullet04]

5 30 all year. I'm in the northeast.

 

[MelsRegal]

To meet EPA gas mileage requirements. I have a 2025 from another GM division. Uses 0W20.
Changed oil at 1,500 miles and switched to 5W30. Noticable slightly higher reading on oil pressure gauge depending on temperature. The oil pump is computer controlled so it will still effect observable pressure.

 

[CorvairGeek]

GM went across the board (in general) in the automotive lines with 5w30 in the 1986 model year. Buick division switched to the gearotor oil pump in the FWD 3.8 and 3.0 V6 in the 86-87 model year. This continued with the 3300 and 3800 V6s. I have always assumed this particular oil pump is why Buick stayed with 10w30 for so long. It was a great improvement over the old, distributor driven oil pump that suffered from wear in the timing cover, and was prone to losing prime.