Interesting test results from the '80s

[Shannow]

Stumbled across this yesterday evening, and found it VERY interesting.

HTHS measurements of a bunch of different oil grades in the mid '80s, prior to HTHS minimums being included into the J300.

an see why 10W40 got a bad rap, and the grade was initially given 2.9 min HTHS.

Looking at the lower 95%, seems that there was an "economy" trend in the ILSAC grades, with a reasonable number of the 5W30s not even able to meet the minimum for 20 (post HTHS mins).

Perhaps (surmising), that's part of the reason for many owners manual recommendations not trusting the 5W30 grade at reasonable ambients.

 

[Garak]

Nice find, Shannow. It definitely seems that modern 10w30 and 5w30 ILSACs have tightened up around a much closer HTHS.

 

[Y_K]

Where is 2.9 in the table?

 

[camrydriver111]

If 10W40 got a bad rap, 5W30 and 10W30 are all lower. Why didn't they get a bad rap? Who gave it a bad rap?

 

[Shannow]

Originally Posted By: camrydriver111
If 10W40 got a bad rap, 5W30 and 10W30 are all lower. Why didn't they get a bad rap? Who gave it a bad rap?


If you review the literature of the day, the problem was that multigrades weren't living up to the protection that their grades implied...the 10W40s (many of them) were incredibly unstable in shear, and provided much less protection (HTHS) than even a bog standard SAE 30 mineral.

They established two "splits" in the 40 multigrade, one for 15W, 20W, and 25W 40s at 3.7 HTHS, and the 10W and lower at 2.9 HTHS, just the same as the 5W and 10W30s.

The 2.9HTHS 40s provided similar protection to the 2.9 HTHS 30s, but had much more VII polymers, and were inferior in that they were more polymer based, had lower viscosity base oils, higher volatility, and by having 40 grade KVs were needlessly wasteful of energy in low shear regimes.

This has only recently been upped to 3.5. for the 40s, which means that they ARE better (HTHS wise) than the 30s

 

[Garak]

Originally Posted By: Y_K
Where is 2.9 in the table?

It isn't in that table. You have to look at older versions of SAE J300.

 

[Shannow]

Here's 1984, pre-dating that study, and the inclusion of HTHS in the ratings.

and 1993, after HTHS was included.

and 2013 after they "fixed" the 40 grades.

 

[SR5]

They fixed the 40 grade, but now they need to fix the 50 ( & 60) grade.