Originally Posted By: A_Harman
Originally Posted By: oilboy123
The new grade’s kinematic viscosity limits
were set at 6.1 mm2/s minimum to
s maximum, at 100 degrees C.
Its minimum high-temperature high-shear
rate viscosity is 2.3 mPa•sec at 150 C.
...the updated SAE J300 standard will require tweaking
the kinematic viscosity limit at 100 C
for SAE 20 engine oils. The current minimum
KV100 limit for SAE xW-20 oils is
5.6 mm2/s, but that will rise to 6.9
mm2/s when the revised standard is published
in April.
Covitch said API, ACEA and others who
set engine oil specifications have the
option of retaining the current 5.6 mm2/s
minimum KV100 for stay-in-grade viscosity
if they wish, but the new-oil minimum
for SAE xW-20 will be 6.9 mm2/s as of
April 2013.
The significant difference in the SAE 16 grade is the min HTHS of 2.3 versus the SAE 20 min HTHS of 2.6. The KV specs that SAE has hung on it are silly:
Old 20 was 5.6 to 9.3 cSt
New 16 is 6.1 to 8.2
New 20 is 6.9 to 9.3, but can sometimes be 5.6 to 9.3.
So if you have an oil with KV100 of 7.7 and an HTHS of 2.7, is it a 16 or 20? It meets both specs, and can still be called a 16 because SAE does not call out a maximum HTHS for a grade.
If that table just above is correct, it will be total confusion in the 16 and 20 grade camps, because the EU folks will probably stick with the old 20 group whilst the US changes to the new groups, that will result in some oils being sold under 2 different labels. Seems to be a repeat of the argument over the definition of the term fully synthetic, they can't even agree over that term within the EU, as the UK followed the US definition downgrade. This could lead to an oil being advertised as an 0/16 full synthetic in the US and as an 0/20 HC synthetic technology in Germany, assuming Cowitch is correct and the ACEA folks stick to the old figures as I suspect they will. Next thing the engine folks will have to change the oil fill caps!!