Quote:
Originally Posted by LostCause
75W90 is equivalent to 5w30 I believe. Transmission fluid and Engine oil use two different viscosity ratings.
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That's the first I've read about dual viscosity rating systems for gear vs. engine oil. Can you point to a source about that?
I can tell you that 75w90 gear oil is absolutely not the same viscosity as 5w30 engine oil, because I compared them by pour testing at the same temperature through a filter. There's a dramatic difference.