Vehicles with optional engines that use a different viscosity

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Snagglefoot

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I came across this page in a owners manual for a 2021 Chevy Malibu. The oil recommendation for the 1.5 Turbo is 0w20, but for the 2.0 Turbo is 5w30. They are both 4 bangers, so the connecting rods and journals of the 2.0 are carrying a larger load. Not sure if the rods and journals of the 2.0 are beefed up more than the 1.5.

So, did the Chevy engineers decide 0w20 can’t cut it in the 2.0? If so, if you were the owner of the 1.5, would you decide to use 5w30? What say Bitoggers.

FC677B66-2D43-4EF7-9997-DC601B289189.jpeg
 
The plot thickens. Don’t mind the pun. The 2.0 came out in the Malibu in 2013 and 5w30 was recommended in all the Malibu engines. Here is the page from the 2013 owners manual. When the 1.5 came out, they recommended 0w20. Sounds like a CAFE thing.

C3E23823-31BE-4942-B98B-1FF0E737487E.jpeg
 
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It may well be driven by CAFE - it may also be informed by an oil cooler. If one of the engine options has an oil cooler, then that engine won’t see the higher oil temperatures that would require an oil in a higher grade.
 
Snagglefoot said:
I came across this page in a owners manual for a 2021 Chevy Malibu. The oil recommendation for the 1.5 Turbo is 0w20, but for the 2.0 Turbo is 5w30. They are both 4 bangers, so the connecting rods and journals of the 2.0 are carrying a larger load. Not sure if the rods and journals of the 2.0 are beefed up more than the 1.5.
Click to expand...

There are assumptions going on here and I don't know if they are accurate or just guesses ....

The "larger" engine could be of a larger bore; that would make for a larger piston. But it's a false assumption to believe that the piston causes more "load". It could be that the piston is of a lighter design or material. The larger displacement could come from only the stroke; using the same piston. None of the info you provided helps us understand what's in play here.

To understand the loads on the main journals and rod journals, the following info is needed:
- journal diameter
- journal width
- piston weight (with rings and pins installed)
- rod weight
- crank stroke
- etc

Larger journals displace "load" better (via more surface area). But even the word "larger" doesn't tell us enough. Journals with bigger diameters also have higher surface-speeds; this causes a higher shear-speed at the face of the bearing. Journals with greater width don't have this issue, but they can contribute to greater alignment concerns.

Everything in life is a tradeoff.

As to the topic of different grades for these engines, it could be an intended difference due to engineering nuances, or it could be an oversight in writing of the manual. (not every owner's manual is without error, after all ....)
 
0w20 is the only recommendation for the 1.5T in various (because i can't say "all") countries under the guise of Vauxhall and Opel; including the UK and Germany
 
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There's a vehicle manufacturer named Vauxhall? Never seen around Detroit and between work and personal use, I travel 20-25k per year all over the Metro Area.

I'll look a little harder to find one - beginning today.
 
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