Thin to thick oil converts?

[wemay]

 

[zeng]

Originally Posted By: Shannow
Originally Posted By: Doug Hillary
People may forget that 20W-50 was a specific lubricant viscosity developed by Duckhams (Q20-50) in 1958-9 to compensate for the poor technical attributes of the BMC Mini. It became the do-all lubricant for many !


Good to see you posting more Doug...

Similarly in these dscussions, I'm paitned as a thick advocate...the L67 in my Caprice is 20W50 as per the manual, but gets 5W30/10W30 A3/B4, my Nissan Navara was specced 15W40, got 5W30 A3/B4, the Captiva is specced 5W40, gets 5W30 Dexos2/C3.

Welcome back Doug, but Shannow btw .. I am a thick practitioner .
I'd replaced:
80W90 with SAE 140;
5W30 UTTO with SAE 140;
15W40 with 20W50 depending on circumstances;
AW46 with AW68, at times mix AW100;
.... and selected xW40 in Mitsubishi's calling for xW30 to xW50 and in Kia's and Yota's calling for xW30 to xW40.
There is such a thing as pay less for 'more' in oil grade selections though ....
Maybe it's just me.

 

[Saxon78]

Originally Posted By: oil_film_movies
If you look at a bunch of UOA's, you'll see oil many times thickens in normal OCI's.


I hardly saw any case of.
I admit I'm not a UOA fan, but I looked at quite a lot here, and especially on oil-club.ru/.de

I hope you compare the Visc from the UOA with the same oil's visc in VOA ... not with the Visc from the preceding UOA (as many do)...

All I saw was a huge bunch of 40's and sometimes 30's thinning out to a lesser grade.

It's enough to compare the UOA 100C visc with the official SAE J300 visc classification
SAE J300

40's: 100C visc between 12.5--16.3cSt
30's: 9.3--12.5
20's: 6.9--9.3

For some reason, it seems that 20's aparently do better (larger oil sumps? less shear/VII? IDK)

How many UOA's show oil going UP a grade?

Let's see the general trend, not the exceptions.