Originally Posted By: merconvvv
So gm 5w30 has hths of around 3.5 ?
Gm 5w30 and mobil 5w40 have almost similar hths?
Am i reading the chart correctly ?
Yep,
it gets back to what I've been saying forever...they knew that when they went to multigrades across the board that the kinematics on J300 stopped accuratelt defining what an oil can do. So they tested and proved that HTHS was the answer, THEN set a bunch of minimums for each grade, and initially gave the 0W, 5W, and 10W40s the same minimum as a 30.
The grading should be xW-HTHS, with the kinematics as the secondary factor.
Per the apparent cofusion on the GM oil...the Delco 5W30 on the shelves locally is Dexos 2, i.e. above 3.5 HTHS.