So... is GC really so shear stable?

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Check this out; let me know if I've made any errors...

For the first two cars I'm using a VOA viscosity of 65.9 (which is the average of 65.8, 65.8, 65.9, and 66.2, gathered from 4 Blackstone virgin reports)

And for the third (Patman's sister's car) I'm using Patman's VOA viscosity of 12.2. Patman, are those viscosities from the same lab? (Wearcheck?)

code:

car miles UOA visc %visc loss

Toyota Sienna 4648 62.0 5.9

Honda Civic b16a 5279 62.8 4.7

Honda Civic 5500 11.5 5.7


Hmmm...

[ October 06, 2003, 10:49 PM: Message edited by: quadrun1 ]
 
The only way to really judge is to compare the VOA vis of the SAME oil you're doing the UOA on, not an average vis from a bunch of different VOAs. We'll be finding out how well this oil has held up in my Chrysler shortly.

FWIW, I think any multigrade oil is going to shear some. "Shear stability" is a relative thing, and relatively speaking, the GC seems to be shear stable.
 
How 'bout these shear numbers I figured a few weeks ago?

Or these recalculated shear numbers I figured the next day? (I threw out the worst example.)

Yes, I'd say EC 0W-30 looks very good too.
Almost as good as M1 0W-40 ...
wink.gif
 
Yes, both the virgin sample I sent and the UOA on my sister's car were from Wearcheck. The one thing though is that the oil I put in my sister's car was from a different batch than the VOA oil, so it is possible her oil was slightly different in viscosity. Also remember, it was her first run with GC, so there is a little bit of the thinner M1 mixed in there. Her second UOA (which I'll have in a couple of weeks) will be the better one to see for viscosity. And my own UOA (due next week) will be good too, since before I put in the GC I have now, I ran a 3L rinse cycle to try and get close to 100% GC in my engine for this run. And the batch in my car is the same as the VOA too.
 
quote:

Originally posted by Eiron:
How 'bout these shear numbers I figured a few weeks ago?

Or these recalculated shear numbers I figured the next day? (I threw out the worst example.)

Yes, I'd say EC 0W-30 looks very good too.
Almost as good as M1 0W-40 ...
wink.gif


Eiron,

You just don't give up do you?
grin.gif
Well, neither do "we," so here's to healthy and collegial competition.
cheers.gif


[ October 07, 2003, 01:08 PM: Message edited by: pscholte ]
 
There are some good M1 numbers too!

M1 0W-40 in G-Man's Olds minivan (4200 miles) thinned only about 1%

After 5,000 miles in an Audi S4 twin-turbo and also after 5K in an Audi 1.8T, M1 0W-40 thinned about 6%.

In the S4, the M1 0W-40 wear numbers were about that same as Amsoil S2K.

I think it's a close call, these are both very good oils!
 
What we really need to see is someone run 2 intervals with 0w40 M1, then two intervals with GC 0w30, in the same engine, in order to see the behavior of the two.
 
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