viscosity modifiers
- Thread starter Killer223
- Start date
You startv with a thinner oil mix than you need after the VM is added, so something like 0W becomes 5W-40, or even 10W-50
Don't forget Pour Point Depressants....
Modern oils can vary from 3cSt to 10cSt+.
https://www.my-cardictionary.com/lubrication/engine-oil.html
As example:
https://www.stle.org/images/pdf/STLE_ORG/BOK/OM_OA/Base Oils/GTL Base Oils_Nov15 TLT.pdf
https://www.infineuminsight.com/en-gb/articles/uncertainty-ahead-for-base-stocks/
https://www.my-cardictionary.com/lubrication/engine-oil.html
As example:
- 78% base oil
- 10% viscosity improvement additive (to improve flow)
- 3% detergent (detergent substances which clean the engine)
- 5% dispersant (for the suspension of dirt particles)
- 1% wear protection
- 3% other components
https://www.stle.org/images/pdf/STLE_ORG/BOK/OM_OA/Base Oils/GTL Base Oils_Nov15 TLT.pdf
https://www.infineuminsight.com/en-gb/articles/uncertainty-ahead-for-base-stocks/
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Viscosity decreases as temperatures rise. VM aka VII reduce the reduction in viscosity as the oil heats up.
IOW all else being equal an oil without VM will have a lower viscosity at operating temps vs an oil with VM.
Note: The winter rating on the label is not the starting viscosity. 5w doesn't mean 5 grade when cold.
0W oils or oils starting with a good base, have a higher natural vi and require less vm if needed ... Theoretically speaking off course since I read that on the internet. 
Having said that, I prefer narrow(er) spread oils like a 10W-30 over wide spread oils like a 0W-40. Some 10W-30s have very little or no vm!
Most people don't need a 0W! Refer to CCS & MRV charts in SAE J300. Unless your engine requires some fancy Euro spec that comes only in a 0W-40 flavor.
Having said that, I prefer narrow(er) spread oils like a 10W-30 over wide spread oils like a 0W-40. Some 10W-30s have very little or no vm!
Most people don't need a 0W! Refer to CCS & MRV charts in SAE J300. Unless your engine requires some fancy Euro spec that comes only in a 0W-40 flavor.
For low cost oil most likely a thin oil base with VII that "thicken" it when heated up. For higher cost oil designed for long drain, they usually start with a better more consistent blend of base oil that was already something like 0w20 or 5w30 without needing anything at the benefit of less volatility (evaporation) and therefore less chances of running low within the OCI.
Grades with a big Winter/SAE grade spread like 0W40 and 5W50 for example, typically have elevated VMs in their additive packages.
The advantage these grades have over 15W40s, 20W50s or single grade engine oils is that they will maintain the desired oil pressure without the corresponding increase in power robbing or redundant HTHS.
This is made possible by the temporary thinning of the lubricant in the bearing space at rpm, by the VMs losing their thickening affect called something shear.
The advantage these grades have over 15W40s, 20W50s or single grade engine oils is that they will maintain the desired oil pressure without the corresponding increase in power robbing or redundant HTHS.
This is made possible by the temporary thinning of the lubricant in the bearing space at rpm, by the VMs losing their thickening affect called something shear.
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