75w140 in 02 Silverado

[1BadManVan]

I recently acquired a used 02 Silverado 1500 with the 5.3, 261k kilometres on it, it also has the 3.73 gears with the locking diff in it. Truck was definitely abused in its prior life. Had to have the whole fuel system redone after discovering dirt throughout the fuel system and no fuel filter.

So while it was in the shop, I had him go over the rest if the fluids in the truck. Probably never been changed ever but the rear diff still looked in great shape. He recommended running a heavier weight and put in 75w140 in it. I know the manual calls for 75w90. Is it going to hurt anything running this heavier fluid?

The truck is mainly used for work around our house, hauling dirt, gravel, garbage runs etc. won’t be my daily

 

[kballowe]

You're fine.

 

[benjy]

only your mpgs will suffer, you can go midrange 75-110 + redline if its not too $$$$ for you

 

[1BadManVan]

only your mpgs will suffer, you can go midrange 75-110 + redline if its not too $$$$ for you

Yea that’s no an issue for me, not a daily driver. Just want to make sure it’s not going to hurt anything since it’s already in there now lol

 

[Kira]

1) No fuel filter or just a non-serviceable fuel filter in the gas tank?
2) How was the coolant?
3) Best of luck with it.

 

[1BadManVan]

1) No fuel filter or just a non-serviceable fuel filter in the gas tank?
2) How was the coolant?
3) Best of luck with it.

Fuel filter and the metal lines were removed and replaced with a rubber hose. Fuel filter on these runs along the frame just under the drivers seat. Literally had dirt/mud in the fuel rail and injectors. Dropped the fuel tank, cleaned that out, new fuel pump, new fuel filter with braided lines, new injectors, fuel rail, regulator etc. This "cheap" truck turned quite expensive pretty quick lol. Also new plugs, wires, coils, new intake manifold, exhaust... Turned into a bit of project truck now lol. But it runs great after all that

Coolant surprisingly looked ok but that will get flushed next. Brakes and fluid on the list as well

 

[wwillson]

75w140 in your climate isn't a great choice and there will likely be no benefit to your differential with a viscosity greater than 75w-90.

 

[Kira]

Locking diff ...mechanically locks so no LSD clutches....still work?
That's Positrack, right?

 

[1BadManVan]

75w140 in your climate isn't a great choice and there will likely be no benefit to your differential with a viscosity greater than 75w-90.

I wasnt the one doing the work, i had planned too but the fuel system issue was out of my comfort zone so the shop did the rear diff while it was there and they had put the 75w140 in it. Is it worth draining it again and replacing with 75w90 if the 140 is already in it?

 

[1BadManVan]

Locking diff ...mechanically locks so no LSD clutches....still work?
That's Positrack, right?

I believe so, not super familiar with chevy trucks, my first one and only had it a month, most of that month being in the shop chasing these issues lol

 

[wwillson]

I wasnt the one doing the work, i had planned too but the fuel system issue was out of my comfort zone so the shop did the rear diff while it was there and they had put the 75w140 in it. Is it worth draining it again and replacing with 75w90 if the 140 is already in it?

How cold does it get there in the winter?

 

[1BadManVan]

How cold does it get there in the winter?

Not very cold, i live right near Vancouver, -10c at the most. Usually doesnt even go below freezing

 

[kballowe]

Just rambling here.... We have several motorcycles where the earlier models spec'd 75W-90 in the transmissions and final drive pumpkins. They're all spec-ing 75W-140 now. I don't know why that is. Harley (forever) wanted their special fluid in the transmissions and primary chain cases. Something akin to a 40 grade hydraulic fluid. Now they are hawking their special blend of 75W-140 gear oil.

Especially being an older vehicle with some wear and tear - I would not have an issue with 75W-140 in the rear differential.

 

[1BadManVan]

Just rambling here.... We have several motorcycles where the earlier models spec'd 75W-90 in the transmissions and final drive pumpkins. They're all spec-ing 75W-140 now. I don't know why that is. Harley (forever) wanted their special fluid in the transmissions and primary chain cases. Something akin to a 40 grade hydraulic fluid. Now they are hawking their special blend of 75W-140 gear oil.

Especially being an older vehicle with some wear and tear - I would not have an issue with 75W-140 in the rear differential.

Appreciate the help, time to save up some money for the rest of the work needed lol

 

[GMBoy]

75w/140 will be fine and actually most OEM'S use that in the tow package vehicles anyhow.

 

[1BadManVan]

75w/140 will be fine and actually most OEM'S use that in the tow package vehicles anyhow.

Good to know. The primary purpose of this truck to haul things around. 80% of the time it will have stuff in the bed. Already had about 1600lbs of pea gravel in the bed for some yard work, along with a bunch of 4x4 fence posts, concrete bags etc. It will be put to work, but atleast i'll maintain it, unlike its previous owners lol.

 

[THORROMIG]

That gear oil will be suffice. Would imagine better than what came out.

 

[1BadManVan]

That gear oil will be suffice. Would imagine better than what came out.

If it’s anything like the rest of it then absolutely lol. Only thing that actually looks decent is the tranny fluid! Lol

Here’s a few pics of the fuel that came out of the rail and the injectors

 

[Snagglefoot]

75w/140 will be fine and actually most OEM'S use that in the tow package vehicles anyhow.

But not GM. However, in around 2019 the owners manuals said see your dealer. Prior to that is was synthetic 75w90 even in the 2500/3500 pickups. Also, I’ve never seen any bulletin or otherwise that said GM changed the rear fluid for tow packages but I’d be interested in seeing it.

 

[userfriendly]

Either Petro-Canada or Chevron 80W140 goes in everything GM HDs or 1500s. My daughter lives somewhere between Vancouver and Whistler, drives a 3500 Duramax.