When it comes to blueprinted performance engine builds, yes there are.
I dont think that is what was being said.......
Ok, then even so I disagree. We're seeing this on the OE side where 0W-8 is being engineered around in engine design, with main bearings growing larger to increase surface area and accommodate lower MOFT.
You are talking two different things. OE is after CAFE, the discussion was about high power engines, built by engine builders, such as a local guy or the like.
I'm responding to the statement, "No engine is 'built' for a certain grade". I know I gave two different types of examples, but tell me how that makes the blanket statement of "No engine is 'built' for a certain grade" correct when clearly engines are being built to utilize a specific grade.
The context from which the statement was made. It is not really a blanket, because of the context.
I like the phrasing with respect to the 0W-8 situation as them being built to tolerate a certain grade (or grades). Because of course they'll work just fine on a heavier oil. Conventional engines of course do not tolerate oils that thin.
Built to tolerate without excessive wear under most conditions. But not built to require. A higher grade as the OP was asking will not damage.
Yes. You can run 20W-50 in something that calls for 0W-20, nothing is going to get damaged unless the temp is too low and the oil doesn't pump. On the other hand, if you've got an engine that spec's like 5W-40 and you put 0W-8 in it, the odds of it tossing a rod through the side as a result of spinning a rod bearing are quite high.
I find it funny we have to go to extremes. 0w8, vs 20w50........same thing ,close enough.
Exactly. To tolerate very thin oils, you need wider bearings, which only engines designed to accommodate super thin oils have.
i assume this is due to the higher contact area?
Correct.
so the higher contact area, the more bearing surface, the less need for higher viscosity?......but not necessarily less wear?
Yeah, you aren't reducing wear in other areas by going thinner, that's why DLC coatings and a greater focus has been put on the additive package. But of course the heavier oils benefit from these additive package upgrades too and would produce even less wear.
The big end of the connecting rod is subject to tremendous force upon each combustion event. The oil flowing through the rod bearings is cushioning that blow, but with thinner oil film thickness (providing less cushion) you need to make the bearings wider to distribute that force along a larger area, because if the "cushion" of oil is both too thin and too small (in terms of area) then the rod bearings are going to make contact with the crank journals instead of riding on the hydrodynamic wedge of oil.
I wonder to what end?
