‘91 Chevy K1500 5.7L TBI with auto trans and 4x4 fluid change

[VK56VD]

Hi,

I’m looking at doing all the fluids, spark plugs, fuel filter and maybe other things that are needed as I dig in.

Can anyone recommend what fluids need to be used in these?

Looking at replacing the power steering, transmission, transfer case, both differentials, coolant and brake fluid.

Do any of these require the dealer oem such as for the rear differential that has the posi traction?

Any recommendations for spark plugs, wires, maybe the distributor, fuel filter?


The truck has 128k miles on it with unknown history that I bought with 122k on it 5 years ago. It was well cared for but the owner passed away. All I know is that it had a new transmission in it and new exhaust on it when I bought it after looking underneath. It has been trouble free except for a starter replacement I did last year, new tires all around due to dry rot and annual synthetic oil changes and a new air filter.

Any other recommendations such as greasing everything that takes grease?

I was looking into synthetic fluids from amsoil but not sure if it’s a good idea for a vehicle of this vintage to use either oem or Dino fluids it most likely came from the factory with.

Also, does this thing take the dreaded dexcool?

It’s in great shape and I’d like to keep it for as long as possible even though I put less than 1k miles on it per year.

Thanks for the recommendations.

Link to the thread when I first bought it: https://bobistheoilguy.com/forums/threads/thoughts-1991-chevy-pickup-c-k-1500-v8-4wd-xt-cab.281317/

 

[joegreen]

I wouldn't worry about any fancy fluids. These trucks are very durable and reliable. Everything you need can be gotten from the auto parts store. No special limited slip fluid is needed for the rear end even if it has the locking differential. Regular green antifreeze, dot 3 or 4 brake fluid, dex 3 equivalent for the transmission.

 

[D60]

I wouldn't worry about any fancy fluids. These trucks are very durable and reliable. Everything you need can be gotten from the auto parts store. No special limited slip fluid is needed for the rear end even if it has the locking differential. Regular green antifreeze, dot 3 or 4 brake fluid, dex 3 equivalent for the transmission.

So much this. Don't overthink it. Good old ethylene glycol in the radiator.

I'd personally use the least expensive gear oil for the diffs, weight is up to you -- I'd do 80W90ish up front and you can go 85W140ish in the rear if it makes you feel better. Synthetic's fine of course, just costs more.

I'd throw Dex/Merc in the t-case and in the p/s system.

 

[Rob_Roy]

Nice truck. If you are not planning to tow heavy I would just stick to the OEM recommended fluids. 80w90 is fine, no additives needed. You can get Dex III fluid at most farm stores in a 2 or 2.5 gallon container. I like ACDelco for the ignition components and filters.

For 1000 miles per year any multi-purpose grease would be fine. e.g. Lucas Red & Tacky, Mystik JT-6 HT, etc.

I'd throw Dex/Merc in the t-case and in the p/s system.

I think that truck would use power steering fluid in that system rather than ATF.

 

[Nick1994]

Those are great trucks. Valvoline MaxLife ATF would be fine for the transmission and transfer case, and just any old fluid for the power steering, brakes, and differentials.

Here's the specs and service manual:

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[D60]

Anything that rolls thru my shop with a Sag pump (or Ford's horrible C2 pump in OBS trucks) and recirculating ball steering gets Dex/Merc in the p/s system. If it's a problem it hasn't shown itself as such for 20+ years

BITOG thread if you wanna geek out ....honestly it lost my interest after awhile and seems you could justify either position.

ATF in power steering system question

So, many manufacturers spec using some sort of ATF as an accepted or recommend fluid for power steering systems. Some other vehicles spec actual "power steering fluid" , and other even use some "special" type of fluid such as Honda, or some of the Euro cars that call for a Ch-fluid. I have...

bobistheoilguy.com

I just like simplifying and consolidating fluids when practical

 

[VK56VD]

Those are great trucks. Valvoline MaxLife ATF would be fine for the transmission and transfer case, and just any old fluid for the power steering, brakes, and differentials.

Here's the specs and service manual:

MediaFire

MediaFire is a simple to use free service that lets you put all your photos, documents, music, and video in a single place so you can access them anywhere and share them everywhere.

download1347.mediafire.com

View attachment 107133

Thank you

 

[wlk]

Maxlife ATF in the transmission, transfer case and ps pump. Ac delco or denso copper plugs. 80w90 for the diff. Regular green antifreeze and if the thermostat is old, I'd replace it too along w lower radiator hose.
I did my ps pump in my 93 c1500 with Maxlife 15ish thousand miles ago and it has been fine.

 

[Will4]

Hi,

I’m looking at doing all the fluids, spark plugs, fuel filter and maybe other things that are needed as I dig in.

Can anyone recommend what fluids need to be used in these?

Looking at replacing the power steering, transmission, transfer case, both differentials, coolant and brake fluid.

Do any of these require the dealer oem such as for the rear differential that has the posi traction?

Any recommendations for spark plugs, wires, maybe the distributor, fuel filter?


The truck has 128k miles on it with unknown history that I bought with 122k on it 5 years ago. It was well cared for but the owner passed away. All I know is that it had a new transmission in it and new exhaust on it when I bought it after looking underneath. It has been trouble free except for a starter replacement I did last year, new tires all around due to dry rot and annual synthetic oil changes and a new air filter.

Any other recommendations such as greasing everything that takes grease?

I was looking into synthetic fluids from amsoil but not sure if it’s a good idea for a vehicle of this vintage to use either oem or Dino fluids it most likely came from the factory with.

Also, does this thing take the dreaded dexcool?

It’s in great shape and I’d like to keep it for as long as possible even though I put less than 1k miles on it per year.

Thanks for the recommendations.

Link to the thread when I first bought it: https://bobistheoilguy.com/forums/threads/thoughts-1991-chevy-pickup-c-k-1500-v8-4wd-xt-cab.281317/

I suggest using high mileage motor oil plus one quart of Amsoil signature or their OEM synthetic. Run this with a Wix filter for 3000 miles max.
Suction out power steering fluid and use Dexron III which supersedes Dexron II. Buy Amsoil in a quantity to get free shipping and to have enough of their product for your next oil change, trans fluid exchange and their power steering fluid. You can use their Dexron III or power steering fluid, or both. Get their gear oil also. Be sure to clean out all metal powder in the differential, and use a new gasket. Amsoil makes brake fluid. The main thing is to get all the oil brake fluid out. Have a shop do that, unless you are really good at it. For coolant, I favor Hot Shot/ LSI coolant. They have one good for 150K miles. Last but not least, use an oil based fuel additive every tank fill. The transmission fluid will have to be done twice in the first year, so I recommend installing a drain plug in the trans oil pan. Otherwise you will have to drop the pan again (messy). Be sure to change the fuel filter after using the fuel additive. You should have a long lasting car! Enjoy it.

 

[Will4]

Amsoil makes a 75w-110 gear oil. This may be perfect for long gear life and a little better mileage. Consider Bestline engine and trans treatment. This is your chance to use the good stuff, not just any old stuff. Lubricants have come a long ways since that vehicle was made. Good luck.

 

[mobilnissan1991]

Lets see a pic of it. As old as me.

 

[D60]

Lets see a pic of it. As old as me.

He links to an entire thread of his right in Post #1