Auto Trans and Rear End Oil Change Planned...Questions?

[ed1948]

Should I use what GM recommends for the 200r4 and for the G80 rear end? The reason for asking is that 30 years have passed since the printing of the info and I'm sure the quality or characteristics of the lubricants are improved.
Do I use the specified lubricants or the modern equivalents? How about the posi additive?
Thanks
(they say there is no such thing as a stupid question)

 

[pontiacgp]

I would not change the transmission fluid, it's not recommended cause changing the transmission oil can cause problems. For the rear you can use rear end conventional oil and add the posi additive or use synthetic which most have the posi additive in the oil.

 

[L67ss]

Its always a good idea to change the filter....

 

[timo22]

I'm with Pontiacgp on not changing the trans fluid. He is right, this usually leads to problems. If your transmission works well , do not mess with it. If by chance you have a small leak, just keep it topped off. timo22

 

[L67ss]

There is literally no situation where not changing the filter is a good idea. All of the fluid has to go through it. So once it starts being restrictive you start starving it of atf. I have never serviced a trans and had it die from the filter being changed

 

[ed1948]

So I should renew the filter and fill the pan . no flush 'n fill.

 

[L67ss]

Def no flush​

 

[Bar50]

I have had them fail after a fluid and filter change. Look for Dextron/Mercron 3 or 4. The diff lube is the same, add posi additive if it is a posi.

 

[L67ss]

Explain to me how changing a clogged filter will cause a trans to fail? That's like saying if you are 4 QTS low topping off the trans will kill it lol

 

[pontiacgp]

Explain to me how changing a clogged filter will cause a trans to fail? That's like saying if you are 4 QTS low topping off the trans will kill it lol

Filters in transmissions don't clog unless there is an issue with the transmission and then new oil isn't going to fix it. The transmission oil is not exposed to contamination like engine oil is with gasoline and that is why transmission oil looks as new after 100,000 miles as the new oil looks in the bottle.