Originally Posted by SONICMASD
Hi Guys,
I know that in 2003 API revised the specs and split the 75W-90 weight category into 75W-90 and 75W-110. I'm wondering if straight 90W was affected by this year's revisions as well? Like is a bottle of straight 90W oil today, the same stuff as what a manual in 2002 called for?
Thx!
Well...... maybe.
You know that the intended viscosity of the 90 grade gear oil was supposed to be on the lower end of the scale, BUT the gear oil specification was so broad that a 75W-90 and a 75W-110 and maybe even a 75W-140 could basically within the same spec. i.e. a company could simply relabel their "75W-90" as 75W-110". Close enough, they said. The same goes for any "straight grade" gear oil.
The manufacturers understood the scale and pretty much followed the original intent, so the answer to your question ? I would believe that the intended specification for a 90 grade gear oil in 2002 would be the same as 2019.
As you know, the API revised the specs in 2003 - and delineated that huge overlap into a couple more distinct scales.
Are you simply curious, or are you researching a gear oil for a particular specific application ?