How many quarts? (fluid questions)

[24 Karat Brown]

Can somebody do a write up on how much of what kind of fluid we need? Oil, diff, transmission. Please include what motor (4.3, 5.7, 7.4, etc) what type of trans (4l80,nv3500,etc) and how much of what type of fluid. There should be a pinned thread on this already but there isnt. I particularly need info on mine. 1994 TBI 350 (no oil cooler), nv3500, and a posi rear end (not sure on gearing)

 

[someotherguy]

It's in your owner's manual

Richard

 

[RawbDidIt]

It's also available online. Amsoil has it, just look under GMC and poof, everything you need to know.

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[24 Karat Brown]

It's in your owner's manual

Richard

Im aware, but not everybody still has it. plenty of these trucks are missing the owners manual

 

[Hipster]

Im aware, but not everybody still has it. plenty of these trucks are missing the owners manual

It's also in a service manual and you can get one in any parts store or online. Either way the the fluids levels are ultimately verified by sight plugs or a dipstick dipstick. If you can't figure out what fluids go in it without having your hand held you shouldn't be messing with it anyhow.

Or you can be the first. Do the sight a service by donating your time and effort to compile a chart and publish it. Does that work for ya?

 

[RawbDidIt]

Can somebody do a write up on how much of what kind of fluid we need? Oil, diff, transmission. Please include what motor (4.3, 5.7, 7.4, etc) what type of trans (4l80,nv3500,etc) and how much of what type of fluid. There should be a pinned thread on this already but there isnt. I particularly need info on mine. 1994 TBI 350 (no oil cooler), nv3500, and a posi rear end (not sure on gearing)

Side note, the posi gears found in the Z71s are 3.73 IIRC. This can be found by searching your RPO codes.

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[someotherguy]

The potential to get the diff fluid wrong is high when using the term "posi" which has zip to do with anything OEM GMT400.

Richard

 

[RawbDidIt]

The potential to get the diff fluid wrong is high when using the term "posi" which has zip to do with anything OEM GMT400.

Richard

I've was under the impression they were actually limited slip differentials, but this isn't the first time I've heard them referred to as a "posi". I usually just roll with it because it's not worth it to make the distinction, and the only thing I have to go on is the fact that my tires don't lose traction on either side when taking a tight turn, so there must be some slip. Additionally, LSD fluid is what came up when I changed mine out.

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[alpinecrick]

The owners manual often does not distinguish between different options.

As Richard said fill to the fill hole on diffs, transfer cases and manual trans--doesn't matter which diff, TC or trans.

Auto trans are voodoo. When starting with a completely empty system, all seem to vary by at LEAST a half quart one way or the other even when "official" capacities are stated, and even when identically equipped. Probably depends on the temp of the fluid when checked. The GMT400's came with shallow pans, deep pans, with/without external coolers, standard size coolers and HD coolers.

Engines, again the manual doesn't discuss oil coolers and such. My 5.7's take a half pint over 5 quarts, I always put 5 1/2 quarts in when changing oil and filter. 7.4's take 7 quarts, with the external oil cooler my buddy's 1995 K2500 7.4 takes 7 1/2 quarts.

Even when I have pulled the knock sensor on my 5.7's and pulled out the radiator, the amount of coolant I put back in was less than the stated capacity--and that was with a new radiator that is almost an inch thicker than the original rad. And no, I don't have air bubbles........

 

[Hipster]

I've was under the impression they were actually limited slip differentials, but this isn't the first time I've heard them referred to as a "posi". I usually just roll with it because it's not worth it to make the distinction, and the only thing I have to go on is the fact that my tires don't lose traction on either side when taking a tight turn, so there must be some slip. Additionally, LSD fluid is what came up when I changed mine out.

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A G80 "gov-loc" locks by springs and weights centrifugally. A type of LSD. It is a different animal then a clutch or cone style Lsd that works on friction and without a doubt calls for different fluid. Gm nomenclature "posi" would indicate clutches.