Curious question?

[bulwnkl]

I understand your point or question, and I think it's quite reasonable.

I remember that old thread now that you linked it (thanks!), but I don't recall what I'd posted nor why I then deleted it.

Mitch Alsup's point in that thread, and my point here, are the same basic thing: There _appears_ to be a ‘big' difference when we see things like this, but it's small enough to be indistinguishable from, or _maybe_ just above, instrumentation error. In that thread, the test was much closer to what I'd like to see here: Silkolene's racing engine oil compared in two different grades. The 0W20 in that other thread was _not_ the same technology as the other two fluids, and even with _both_ the lower viscosity _and_ the newest technology, the dyno runs didn't show enough difference to overcome instrumentation error (dyno reproducibility).

Things like this happen a LOT— The newest and best technology is applied to a new ‘thing' which is different in multiple ways from the old ‘thing,' but then something other than the new technology is misidentified as _the_ reason for whatever improvement. The conflation of multiple factors means the test isn't actually testing a single factor, and piled on top of that is the fact that there's neither disclosure nor discussion of testing or instrumentation error.

To be clear: Lower-viscosity fluids require less power to pump and flow, therefore they save fuel, just as newer-technology lubes can reduce both wear and power loss vs older-tech ones.

All I'm saying is that the magnitude of the savings between a same-tech 5w20 and 0w20 on a dyno is nowhere near what one might infer from the comparison in this thread.

 

[Bill_W]

There are three things to think about. Base oil improvements. Viscosity spread difference. Oil weight at running temp drag.

The 0w-20 and 5w-20
0w-20 oil with a higher viscosity index improvers but a better starting grade base oil than 5w-20.
5w-20 oil have much less VII but start with a lower grade base oil. Been around for a long time.

The worst that 0w-20 can do is get thinner with time due to shear.

The end result of heavier weight oil would be oil drag. But if you race long distance at high RPM maybe a better choice.

90% of wear happens on start up.

Nothing is black and white but if your car is set up for 0w-20 the oil pump, thermostat, bearing clearance exc. is set up for that grade viscosity and SN or SN+ regardless of the additive package. The top 3 car manufacturers for reliability, Lexus, Toyota and Mazda use 0w-20 grade oil in a 2019 engine.

 

[kschachn]

But unless the temperature is well below 0F, more like -25F or below the 0W and the 5W rated oil will have similar starting viscosity. For all practical purposes 5W-20 is not a "heavier" oil than the 0W-20 and may very well be a lower viscosity depending on the temperature.

And does 90% of wear occur at startup? Where have you seen data to support that?

 

[Bill_W]

Thanks for calling me out on the 90%...
That used to be the shock answer to others a long time ago. Here is a more updated info on a modern engine.

https://www.physicsforums.com/threads/why-most-engine-wear-occurs-during-cold-start-up.929237/

 

[bulwnkl]

Originally Posted by Bill_W
The top 3 car manufacturers for reliability, Lexus, Toyota and Mazda use 0w-20 grade oil in a 2019 engine.


You just conflated _even more_ factors into your old-tech-5w20 vs newest-tech-0w20 post.

 

[Bill_W]

Conflate means bring together, but really does not matter. There is no black and white answer and as long as you get a clear view of the positive and negative ok by me. Cause there is a plus and minus to each action.

 

[Skippy722]

Originally Posted by JLTD
Nope, no noticeable change in economy or performance. I even ran 0w-40 after that and again no differences noted.


I just switched both cars over to 0w40, other than seemingly being a little quieter, they both seem happy on it.