What does the mineral oil do in a transmission change?

[ouroutdoorfamily]

I was reading up on changing the fluid in my transfer/transmission and I came across this repo and I'm not sure what it means:

Join Date: May 2003
Posts: 3,110
Do a drain and fill with mineral oil (about 4 quarts), run it for a few thousand miles, do another drain and fill, run a few thousand miles, and then do a third drain and fill. After that do it every 15k miles or so. Unlike most american cars, the LC does not use a paper filter that can clog up very easily.

I have an 83' FJ60, stock engine, tranny and transfer. I think it's been awhile since mine has been changed, so Id like to do something more than draining and re-filling.... unless it simply is not required?

 

[GeologistFelix]

It's cheaper than the fancy stuff, and it gives any sludgy stuff a whole refill worth of clean oil to dissolve into, which gets a fair amount of it loose. If you just drained and refilled with the fancy stuff, it would get fouled fairly quickly and be a big waste of money.

That's my assumption, anyway.

 

[gregnash]

interesting...

 

[GeologistFelix]

I think it's similar to how if a PO has clearly not changed the oil in a very long time, you should run diesel motor oil (for the detergent) with a super cheap filter after draining the old oil, for maybe a few hundred to a thousand miles, to get all the nasty stuff cleaned out gently, then drain and put on the good quality filter and fill up with your fancy oil.

Which makes me wonder, could it hurt to put half a quart of 20W-50 diesel oil in with your gear oil and then run it for a while?

 

[Wile E Coyote]

IIRC correctly, the largest component of tranny fluid (Dexron III) is mineral oil. I personally would just stick with using tranny fluid for my flushing procedures.

 

[Godwin]

Just drain the old gear oil and replace it with fresh gear oil. If the oil has been contaminated with water change it, drive it some, and do another drain and replace.

I think the post the OP copied refers to an auto tranny and not a manual.

 

[Cruiserdrew]

Just drain the old gear oil and replace it with fresh gear oil. If the oil has been contaminated with water change it, drive it some, and do another drain and replace.

I think the post the OP copied refers to an auto tranny and not a manual.

X2



Only run gear oil in your transmission, unless you want it to fail. It's designed for GL5 gear oil. If you want to "clean up" the transmission, do a short change cycle of say 1000 miles. It's all the transmission will need and anything else, especially mineral oil with no pressure additives will cause the mating surfaces of the gears to wear quickly. What is posted above is extremely bad advice and should not be posted here as a recommendation.

It's bad advice for either an automatic or a manual.

 

[Mark W]

X2

Only run gear oil in your transmission, unless you want it to fail. It's designed for GL5 gear oil. If you want to "clean up" the transmission, do a short change cycle of say 1000 miles. It's all the transmission will need and anything else, especially mineral oil with no pressure additives will cause the mating surfaces of the gears to wear quickly. What is posted above is extremely bad advice and should not be posted here as a recommendation.

It's bad advice for either an automatic or a manual.

Yep. The idea that there is some sort of sludge or goop in an auto or manual transmission that needs to be flushed out is erroneous in the first place.

If you get water in either, drain it, put new fluid in and check it after a short period to see if there is any sign of residual contamination. Running incorrect fluids in your drive train is asking for failures. It is not mysteriously going to help any thing.


Mark...

 

[Zack1978]

X2



Only run gear oil in your transmission, unless you want it to fail. It's designed for GL5 gear oil. If you want to "clean up" the transmission, do a short change cycle of say 1000 miles. It's all the transmission will need and anything else, especially mineral oil with no pressure additives will cause the mating surfaces of the gears to wear quickly. What is posted above is extremely bad advice and should not be posted here as a recommendation.

It's bad advice for either an automatic or a manual.

The only thing I would say is to use GL4 spec oil, like Redline MT-90 or the Amsoil GL4 gear oil. I know that most people say GL5 is just fine, but why take the chance when GL4 is available. I think it has something to do with certain soft metal parts having a tendency to wear quicker in GL5.
In my 60 I used Redline MT-90, and it made the shifting much much better and smoother.

Zack