Castrol Classic EP90

[MechRookie]

Has anyone tried Castrol Classic EP90 for steering box, gearbox, or transfer case? I’ve read through past threads about different GL-4 options, but am about to tackle my first gear oil change and wanted to see if anyone had tried the Castrol.

Thanks.

-Nick

[TedW]

Hi Nick,

Just my opinion: I use Amsoil GL4 synthetic gear lube, as it runs cooler in the summer and remains fluid in the winter for easy gear changes when cold. And no, it doesn't leak out any faster than conventional gear lubes. Available at most NAPA locations.

Just my $0.02 - you will get lots of varying opinions if you keep asking.

Ted

[jimrr]

yes, i put castrol 90 wt. in my gear boxes before trip thru mexico. i could tell the difference when coasting down hill, it REALLY made a difference. I didn't do a mileage check but i know it of course got better mileage.
DO NOT use anything with even a hint of seal swell in it ........... my dump truck now need all the cylinders rebuilt, you're better off with a slow leak that seals like jello !!

[MechRookie]

Thanks for both your thoughts, I appreciate the insight.

-Nick

[MechRookie]

TedW,

Is that the 75W90 AMSOIL?

[TedW]

TedW,

Is that the 75W90 AMSOIL?

Yup - Manual Transmission & Transaxle Gear Lube 75W-90 GL-4. GL-4 (vs. GL-5) is specified for our gearboxes as it is friendly to the brass / bronze components within. GL-5 lubes have additives that are said to have negative effects on the bronze bits. It's a bit more complicated than that, but that's a subject that's been beaten to death over the years.