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Mack 5 sped with Tetrapoid gears


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90W gear lube in all. I use GL-4 as that was what was available when those trucks were on the road. GL-5 has extreme pressure additives that is not, (or used to be not) so easy on brass parts inside of transmissions. I stay with GL-4 for this reason.

Dog.jpg.487f03da076af0150d2376dbd16843ed.jpgPlodding along with no job nor practical application for my existence, but still trying to fix what's broke.

 

 

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  • 3 weeks later...

I drained the transmission and compound unit oil from my 1964 B61 5 speed.  1.5 pints of  clean red oil came out.  I can only guess why a prior owner or technician would do that.  The oil looked unused.  The magnetic plug showed signs of use as the photos show.  The Mack operator's manual specifies SAE 140 Straight Mineral Oil where the ambient temperature is above 50 F.   My local NAPA store carries a SAE 90 Mineral Oil but not the 140.  I can get SAE 140 Mineral Oil online and maybe from a local oil supplier.  I read online that the EP additives are not good for the yellow metals in the transmission so I'm staying away from that. 

Is there a modern gear oil that is as good as the mineral oil Mack specified back in the 60's?

Thanks

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trans_magnetic_plug_clean2.JPG

Edited by HugeHugh
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Run straight 90W GL-4 gear lube and you'll not have any problems. GL-5 will work in non syncronized transmissions but GL-4 does not have the extreme pressure additives that are corrosive to yellow metals. GL-4 was what the truck was filled with when new most likely.

If you only drained 1.5 pints it was either short filled, or there is a leak. ATF does not belong in that transmission at all but they probably dumped it in thinking the trans was hard to shift rather than the linkages being corroded.

Don't get "wrapped" around the axle with the terminology. Straight 90W is good, 85-140 will work also in your transmission. Fill it, drive it, allow it to cool, then top off the transmission oil. Watch for leaks until proven otherwise.

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Dog.jpg.487f03da076af0150d2376dbd16843ed.jpgPlodding along with no job nor practical application for my existence, but still trying to fix what's broke.

 

 

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I tend to takes things literally and that's why I was asking.  I figured 50 years of lubricant development may have created suitable substitutes to a 1960's SAE 140 mineral oil.

The red oil that came out of the transmission was much thicker than any ATF I've seen, but the color was similar. 

Thanks

 

 

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There is a company called "Red Line" lubricants and some of their oils are red in color. Usually their stuff is quite "sticky" in consistency too. However, only 1.5 pints is not near sufficient to both lubricate, and cool that transmission. 

Dog.jpg.487f03da076af0150d2376dbd16843ed.jpgPlodding along with no job nor practical application for my existence, but still trying to fix what's broke.

 

 

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I bought a 5 gallon bucket of SAE 90 and started filling the transmission.  In about 10 minutes the leak appeared in the PTO assembly on the side of the transmission.  One of the drain plugs was missing from the PTO and the other one was only 1/2 way screwed in.  I replaced the missing drain plug and secured in the other one and finished filling the transmission.  I checked the rear axle and it was empty too.  I suspect someone in the past needed gear oil and decided to drain it from this truck as it sat unused.    

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I've never seen a PTO with a drain plug. Is this a Chelsea, Muncie, (same thing) or other branded unit?

Dog.jpg.487f03da076af0150d2376dbd16843ed.jpgPlodding along with no job nor practical application for my existence, but still trying to fix what's broke.

 

 

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3 hours ago, Rob said:

I've never seen a PTO with a drain plug

Here in Australia, I've never seen a PTO without a drainplug...

"Be who you are and say what you feel...
Because those that matter...
don't mind...
And those that mind....
don't matter." -

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