Changing all fluids. Need advice

[markedgar5]

I'm looking to change all fluids and filters in my blazer as soon as I get it back from the paint shop. Is there a sticky or possibly a thread i havent found yet on what fluids are recommended as far as viscosity and any needed additives. 72 blazer orig eng/trans. 350 cid v-8 (1ls910) engine, automatic (1m4910 (turbo hydromatic)) trans. 3.73 rear axle (1hq510)PS, PB, 4x4.

I plan on changing and flushing when possible.
Power steering fluid
Brake fluid
Gear oil
Transmission fluid
Engine oil
Transfer case
The more I search the more confused I get as to what to use. Necessity of friction additives etc. I will likely go full synthetic unless for some reason it shouldn't be used in the older trucks. Thank you for any advice, I greatly appreciate it.
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[Rufton]

Couple things I'd consider.
When bleeding brakes don't push pedal farther than normal travel.
When changing tranny and PS fluid, disconnect return line and add fluid into reservoir while old fluid is pumped (engine running) into container.

[markedgar5]

Thank you for the advice. I will definitely use the tips. I'm probably over thinking everything but seems like this is the place where people care about their trucks as much as I do.
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[70-K5]

I use Valvoline VR1 in my motor, basically because that is when the builder told me to use. It is one of the only oils left that has zinc added to it, good for camshaft and valve train. Personally I use 20/50 but depending on your climate and the condition of your engine the specific weight could be different.

Unless you have a posi unit in your differential you don't need to worry about additives. The additives are there to help the clutches work, they have nothing to do with the gear on gear contact in the differential. So good old 80-90 or straight 90 weight gear oil will be just fine if you have an open differential. This is the same fluid you should put in your NP205. The 205 takes gear oil, not transmission fluid like the later chain drive cases or 30 weight oil like the hybrid NP203, gear oil.

I would be cautious changing the transmission fluid. Over time as the clutches and bands wear they leave a tiny bit of that friction material in the fluid. If you drain 100% of the fluid your transmission could start to slip because you just removed that material. This does not happen every time but it is possible. Depending on the age of your transmission and how it functions you would be better off changing only the fluid in the pan and the filter. There is much more fluid in the torque converter that you don't need to flush unless the fluid is very dark and smells burnt. There are different types of fluid: Type F, Dextron, Dex/Merc, and probably a few others, but those are what you see on most parts shelves. I have seen debate on which brand to use depending on the application. I use Dex/Merc. As far as I know the Type F is for Ford transmissions, I think the F is just a coincidence.

[truckster]

I agree on the trans fluid. I've seen way too many that stop working after a fluid change, especially if they've got high mileage.

[markedgar5]

I'm glad you brought that to my attention about the trans fluid. Never realized changing with fresh fluid could cause issues.
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[Rufton]

I've seen OEM fill dino gear oil last decades in rear and manual trans. I've changed those fluids w/o issue. The dino gear oil is good enough for me. Upon rebuilding trans and rears I've been impressed w/ dino gear oil performance of low wear. I have encountered pitting and grind em find em wear but not sure synthetic would help those issues.

I've seen OEM fill (w/ user topping for leaks) auto trans fluid last decades until seals finally get brittle and start causing issues. I have changed auto trans fluid w/o issue or improvement. Sludge does accumulate in VB but fluid change probably won't clean it out. I'm impressed how clean old auto trans fluid is.

Old brake fluid will kill brakes. Need to change often.

Regular mineral motor oil can keep properly designed/maintained engine sludge free over 150,000 miles if changed every 3000 miles. Some modern cars sludge even w/ synthetic oil at mfg change intervals according to internet traffic.

Expired coolant additives will kill heater core, kill radiator, pit aluminum and corrode iron. If daily driver coolant is over 5 years old your pushing your luck. Week end driver coolant seems to last over 5 years. Back in the day we used coolant plus tap water and had frequent core issues.

Power steering fluid can get nasty and I like to change every several years. Old pwr strg fluid doesn't seem to be too damaging. Don't know if fresh will better prevent leaks.