Synthetic in Portal boxes?

Diffs, axles, lockers, transmissions, portals, that kind of thing.
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Synthetic in Portal boxes?

Post by AdamH » Tue Apr 03, 2018 4:33 pm

I'v been scrubbing this site and am finding very different opinions about oil that goes in the portal boxes.
Some say use whatever you got, some say stay away from synthetic, some say they use synthetic and its great. Some even say the Synthetic makes seals leak is an old myth from the early days of synthetic.
But most of these posts are form a while ago.
I think theres a consensus that Redline MT-90 is great for the tranny and that the HD Shockproof oil is great for the diffs and transfer case- but not on the portal boxes.
Has anyone run Redline shockproof HD in portal boxes for an extended amount of time with success? It sounds like the right oil for the job- but does it leak?
I don't have heavy tools at my disposal, so I'm trying everything I can to not have to do heavy rebuilding projects.
Any thoughts?

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Re: Synthetic in Portal boxes?

Post by Jimm391730 » Tue Apr 03, 2018 5:05 pm

I have run Valvoline synthetic 75W90 in the hubs for several years with no ill effects. But at some point when it was being serviced by others that was replaced by the "recommended" oil, as specified by Steyr Puch or closest currently available. The long term effects are un-noticable to me - the gears and bearings are so heavy in these trucks hubs that they would run almost as well if you just pee'd in them. Because of the reported damage to the brake shoes if synthetic gets to them I never bothered going back to synthetic.

So to repeat your findings, use what you got or what you want to, as long as you acknowledge the possibility that synthetic could (some will say definitely will) ruin the brake shoes if it ever leaks. I've not found any significant drawbacks to using "old style" gear oil in the hubs and I've put 70-80k miles on my truck. I have noticed increased driveline drag at low temps (before driving enough to warm them up) without synthetic, but this is a minor issue.
Jim M.
712W and 710M

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Re: Synthetic in Portal boxes?

Post by pcolette » Tue Apr 03, 2018 5:46 pm

I've used the Redline MT-90 in both of my 710M transmissions and STA-LUBE SL24239 85-90W in the differentials, transfer case, and wheel drives. I'm been happy with the results, especially the MT-90. I have noticed occasional seepage from various joints but I've attributed it to the changes in ambiant temperatures here in Wisconsin. From mid-Spring to late Fall I rarely notice any seepage or drips but during the Winter when the trucks just sit unused and endure below 0 temps, I can almost count on a few small puddles. If I store the truck in my heated shop for the Winter no drips occur.

As Jim said these trucks are built to handle rough conditions with various lubricants available.
Paul C.
'73 Swiss 710M
'89 Puch 230GE
2002 MB G500

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Re: Synthetic in Portal boxes?

Post by Sonarman » Tue Apr 03, 2018 10:22 pm

I have been running Amsoil gear lube for a year now in the portal boxes, transfer case, transmission. No leaks at all. I did put new copper washers in that I purchased from Expedition Imports.

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Re: Synthetic in Portal boxes?

Post by pinzi » Wed Apr 04, 2018 3:44 pm

I put 80w140 in mine :wink:
off-road until i die

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