Interesting paper, as it covers a number of memes on BITOG
* you need to run two identical engines on different oils to do a meaningful test;
* how do Buick 3.8s fare on different viscosities;
* UOA versus teardown results;
* VII versus deposits;
* High shear viscometry versus Kinematic
* Viscosity versus economy.
What the paper offers...
* same basestock and additives, 4 different VIIs brewed to same KV100;
* 4 identical engines;
* that happen to be Buick 3.8s;
* includes teardown, and touches on UOA;
* looks at deposits with shear stable and non shear stable VIIs;
* recommends gradings based on HTHS;
* touches economy briefly.
http://papers.sae.org/780982/
Quote:
Four multigrade engine oils, containing the same base oil plus SE additive package but VI improvers of differing shear stability, were evaluated in 80 000 km of high-speed, high-temperature vehicle service.
Bearing, piston ring and valve guide wear, as well as oil consumption, oil filter plugging and engine cleanliness were all worse for the engines operated on the low-shear stability oils. The wear differences were traced to differences in high-shear-rate viscosity, while the cleanliness, filter plugging and oil consumption differences occurred because of excessive wear or polymer shear degradation.
These results suggest that engine oil viscosity should be specified under high-shear-rate conditions.
Here's a google books that delivers most of the paper.
* you need to run two identical engines on different oils to do a meaningful test;
* how do Buick 3.8s fare on different viscosities;
* UOA versus teardown results;
* VII versus deposits;
* High shear viscometry versus Kinematic
* Viscosity versus economy.
What the paper offers...
* same basestock and additives, 4 different VIIs brewed to same KV100;
* 4 identical engines;
* that happen to be Buick 3.8s;
* includes teardown, and touches on UOA;
* looks at deposits with shear stable and non shear stable VIIs;
* recommends gradings based on HTHS;
* touches economy briefly.
http://papers.sae.org/780982/
Quote:
Four multigrade engine oils, containing the same base oil plus SE additive package but VI improvers of differing shear stability, were evaluated in 80 000 km of high-speed, high-temperature vehicle service.
Bearing, piston ring and valve guide wear, as well as oil consumption, oil filter plugging and engine cleanliness were all worse for the engines operated on the low-shear stability oils. The wear differences were traced to differences in high-shear-rate viscosity, while the cleanliness, filter plugging and oil consumption differences occurred because of excessive wear or polymer shear degradation.
These results suggest that engine oil viscosity should be specified under high-shear-rate conditions.
Here's a google books that delivers most of the paper.