Differential Fluid Change Question

J Thomas · Sep 22, 2016

I have a 1992 K1500 and I'm not sure what fluid to change out with. I got a fluid spreadsheet from O'Riley's and it notes 80W90 for both differentials. In the note section, it lists the following numbers: 12345836 for the front and 12378261 for the rear. I can't find either. Can I use AC Delco 80W90 and be fine? Also, does anyone know the fluid capacity for the front? Thanks!

RichLo · Sep 26, 2016

The best 80/90 you can afford is better than keeping the stock 1992 fluid in there.

And I usually do a 50/50 mix of lucas oil stabilizer whenever dealing with older differentials

90halfton · Sep 26, 2016

10 bolt axles usually go to s### long before the life of the oil is exceeded. Lol. Any 80w90 will work well. Don't over think it or overspend on magic oils.

Jrgunn5150 · Sep 26, 2016

It's a little under 2 qts up front, and a little over in the rear.

J Thomas · Sep 26, 2016

OK, next question. After calling the dealership and running my VIN and product code in the glove box to the parts guys, he said I have a limited slip rear. I have read when you change the rear end fluid, it calls for an additive. Am I ok to go back with AC Delco fluid, or is there something better out there? Also, does anyone know the additive ratio to fluid ratio? Thanks!

aaronb · Sep 26, 2016

Don't add an additive for the g 80. Just do strait 80/90 gear oil.

Jrgunn5150 · Sep 26, 2016

J Thomas said:
OK, next question. After calling the dealership and running my VIN and product code in the glove box to the parts guys, he said I have a limited slip rear. I have read when you change the rear end fluid, it calls for an additive. Am I ok to go back with AC Delco fluid, or is there something better out there? Also, does anyone know the additive ratio to fluid ratio? Thanks!

aaronb said:
Don't add an additive for the g 80. Just do strait 80/90 gear oil.

This is correct, some people erroneously call the G80 a posi or limited slip. It is in fact a locker and requires nothing more than gear lube.

df2x4 · Sep 27, 2016

X3, no additive for a G80. If you do add it, it will cause your locker to stop functioning properly.

J Thomas · Sep 28, 2016

Should I stay away from a synthetic or does it matter?

Jrgunn5150 · Sep 28, 2016

J Thomas said:
Should I stay away from a synthetic or does it matter?

Doesn't matter, whatever floats your boat there. I have dinosaur oil in mine, I sleep well at night lol.

Differential Fluid Change Question

J Thomas

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RichLo

E I E I O

90halfton

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Jrgunn5150

Enjoying tomorrow's success today

J Thomas

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aaronb

I'm Awesome

Jrgunn5150

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df2x4

4L60E Destroyer

J Thomas

Newbie

Jrgunn5150

Enjoying tomorrow's success today

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