Dirty gearbox oil after 10000ks.

**wovenrovings** · 6th July 2007, 09:52 AM

I am not sure if there is a problem with the gearbox so I though i would ask.

Was checking the gearbox oil level last as part of my 10000 ks service and found it had about 300ml extra, however the oil that came out was black, like used petrol engine oil (not pitch black like diesel oil). Which is not right as the oil is only 10000ks old. I have only owned the vehicle for 10000ks and put all new oil in when i got it. The oil I put in it was Penrite 15W-40 diesel oil. I had it so i used it. So what i wondered is, is something wrong in there making it black (it drives fine doesn't make any unusual noise), or has the diesel oil clean out all the gunge from its previous life? It is a Lt95 in a 84 120. Has 216000ks.

I am going to replace the oil so will look for metal bits. Am thinking of replaceing it with a gear oil. Is this gear box affected by the EP agents?

Thanks in advance.

WR.

**Blknight.aus** · 6th July 2007, 09:58 AM

if you changed the oil and put a fresh lighter weight oil that what was in it in it then id say that the oil youve just put in has cleaned up all the gunk and lifted the stuff that has settled on the bottom of the box which is what youve seen...

This might last for 2 or 3 changes and is nothing to panic about unless you have metal bits in the filter or hanging onto the drain plug.

**Michael2** · 6th July 2007, 11:12 AM

Originally Posted by wovenrovings

...The oil I put in it was Penrite 15W-40 diesel oil. I had it so i used it. ... WR.

have you put motor oil in the gearbox?

**rick130** · 6th July 2007, 06:12 PM

Originally Posted by Michael2

have you put motor oil in the gearbox?

yep, that was the specified lube back then. Downside is It tends to shear pretty quickly and isn't the best for synchro performance.

**jimbo110** · 6th July 2007, 07:51 PM

diesel engine oil is full of detergents and additives to keep all the crap in suspension. you have just cleaned the insides of the gearbox. some times this can clean away crap from around the seals and cause leaks, prob better with a less detergent engine oil or synthetic.

**jimbo110** · 6th July 2007, 07:53 PM

DONT USE GEAR OIL!!!!!! It can shear the teeth off the oil pump!

**Blknight.aus** · 6th July 2007, 08:17 PM

you can use gear oil, you just have to make sure its the right type of gear oil and not the 80/90 type of stuff your thinking about.....

Right off the top of my head AP5 is just marginally more viscous(thats the bit im guessing about) than ATF dexron III and has a better pressure loading characteristics (pressure that it takes to disperse the film it leaves) than dexron III..

**jimbo110** · 6th July 2007, 08:23 PM

Originally Posted by Blknight.aus

you can use gear oil, you just have to make sure its the right type of gear oil and not the 80/90 type of stuff your thinking about.....

correct!
Is AP5 not the stuff that eats brass? Or is that GL5?

**rick130** · 6th July 2007, 08:23 PM

xW-40 engine oils usually fall right at 14.5 cSt @ 100*C, which is what 75w-90 manual trans oils like Castrol Multitrax and Syntrax, and Redline MT90 also sit at.
VMX-M and Syntrans are around 12cSt, and VMX-80 is approximately 10.5 cSt @ 100*C, which is in the range of an xW-30 engine oil.

**Blknight.aus** · 6th July 2007, 09:09 PM

Originally Posted by jimbo110

correct!
Is AP5 not the stuff that eats brass? Or is that GL5?

your thinking GL5 Ap 5 is the new breed of auto fluid.

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