Synthetic Fluids Recommended?

[livestrongroadie]

Hey everyone, just wanted to get your thoughts on some maintenance. Recently got a 1988 K1500 automatic from a family member that only had about 67k miles on it, but wanted to make sure that all the maintenance was on point. I have already changed the spark plugs and wires, flushed the cooling system and p/s system, changed the fluid in the front and rear differential and put in Castrol synthetic gear oil, and probably a few other things I have forgotten about.
Now moving on to the engine oil, transmission fluid, and transfer case fluid, what is your opinion on going synthetic with those things? I know that the mileage is extremely low for that year, but it is also close to a 30 year old truck so I am hesitant. Should I just stick with dino oil for those systems or does the low mileage trump the age? To my knowledge the transfer case also uses transmission fluid correct? If so, okay to go synthetic on that?

On a complete side note, when I drop the pan to do the transmission filter, I was thinking about dropping the valve body and putting in one of those B&M shift kits to sharpen up the shifting a bit. Is this a bad idea or okay given the low mileage? I have a few other small bolt-on performance parts I had in mind, but just curious if that one would likely do more harm than good to a truck of that age.

Thanks in advance for any advice!

 

[Jrgunn5150]

There's no reason not to run synthetic, regardless of age of mileage, if you want to.

There's no reason to run it, if you don't want to.

It's cheap enough now, that it's what I use, and my truck has 200k on it, and is kind of a POS.

The shift kit is a good idea, as is an auxiliary cooler for it.

 

[90halfton]

No mechanic has ever tore apart a thing and said "well.....you shoulda used synthetic, I wouldn't have to work on this if ya did". Like jr said, use what's cheaper, or the one with the prettiest bottle, whatever. I use rotella 10w30 diesel oil partial synthetic (cause it's cheaper right now), cause it's a great oil and cheap.

 

[michael hurd]

Synthetics are a better product than dino oils, and when they are on sale, not much of a price difference between regular priced dino oils.

If you have a G80 locking rear axle and experience chatter when turning, you might need to put in some posi-trac additive in the oil, you can get this from GM.

 

[michael hurd]

Right from Eaton ( FAQ under the Eaton Posi section )

http://www.eaton.com/Eaton/ProductsServices/Vehicle/Differentials/FAQforDifferentials/

Q: What kind of oil should I use? Can I use synthetics? Do I need a friction additive/modifier?
A: Eaton Posi units perform best when using GL4 (or better) mineral/petroleum based gear oil. A four ounce bottle of friction additive/modifier is also necessary for optimum performance.

Q: Is the Eaton Posi Rebuildable?
A: Yes. There are three main types of service kits available - internal spider and axle gear kits, clutch kits, and preload spring & plate kits.

Q: Can I upgrade my Eaton Posi?
A: Yes. Both the clutch disks and the preload springs can be upgraded for extreme off road and drag racing applications. Posi units come equipped with 400lb of preload. They can be upgraded to 800lb, or even downgraded to 300 or 200lbs options. Clutches - There are several types of clutch service kits. They range from the OE, 18 disc (standard), the 24 disc (high performance), and the modern day, high tech 14 disc carbon fiber design.

Q: What is the warranty for the Eaton Posi?
A: The Eaton Posi is guaranteed for one year against manufacturers defects.

 

[livestrongroadie]

I figured for the transmission and transfer case I wouldn't have a problem. I was mainly concerned about using synthetic engine oil as I have read a few bad things about using it in older engines.

 

[beardeddummy]

If I did anything in the transmission it would atf+4 yes I know it's Chrysler fluid otherwise just atf. engine why not synthetic.

 

[beardeddummy]

Right from Eaton ( FAQ under the Eaton Posi section )

http://www.eaton.com/Eaton/ProductsServices/Vehicle/Differentials/FAQforDifferentials/

Q: What kind of oil should I use? Can I use synthetics? Do I need a friction additive/modifier?
A: Eaton Posi units perform best when using GL4 (or better) mineral/petroleum based gear oil. A four ounce bottle of friction additive/modifier is also necessary for optimum performance.

Q: Is the Eaton Posi Rebuildable?
A: Yes. There are three main types of service kits available - internal spider and axle gear kits, clutch kits, and preload spring & plate kits.

Q: Can I upgrade my Eaton Posi?
A: Yes. Both the clutch disks and the preload springs can be upgraded for extreme off road and drag racing applications. Posi units come equipped with 400lb of preload. They can be upgraded to 800lb, or even downgraded to 300 or 200lbs options. Clutches - There are several types of clutch service kits. They range from the OE, 18 disc (standard), the 24 disc (high performance), and the modern day, high tech 14 disc carbon fiber design.

Q: What is the warranty for the Eaton Posi?
A: The Eaton Posi is guaranteed for one year against manufacturers defects.

Anyone have any links to rebuild kits for the posi can't afford a new maybe this will get me buy

 

[GL1500]

My .02.....I believe that regular oil changes (and a clean air filter) will have a much greater impact on the longevity of any internal combustion engine than dino/synthetic oil. If you've ever torn down an engine that's been neglected of oil changes it'll make you a firm believer in regular maintenance.

 

[TylerZ281500]

the bad things you read on synthetic engine oils is because of oil deposits clogging holes in gaskets, since syntheteic is such high detergent it means that whatever filth is in your engine will slowly start to go away as it cleans it, which isnt bad but someteimes leads to oil leaks where gaskets have failed. another thing to keep in mind is your engine is roller, you can run whatever youd like, same as flat tappet but, you need a zinc additive