10w oil for Unimog transmission

[m37charlie]

By the way, the 435s (6 bolt wheels) can develop a situation where the portal pumps oil into the diff thru the breather line, especially in the front.
"Von" on the benzworld forum has developed a relatively inexpensive fix for this. Have you driven yours enough on long distance high speed trips to be absolutely sure this isn't a problem? It's pretty easy to lose ~200ml of portal oil into the diff and destroy portal bearings and have a very bad day.
The fix is just a bit of metal tubing plumbing that attaches to the breather outlet and fill openings on the inner aspect of the portal box, just takes a couple of minutes to install.

Charlie

 

[frenchian]

Ive heard of the "portal pump" problem - for some reason my truck is low geared and is only really comfortable up to 40mph - anything more and you are deafened within half an hour. I therefore drive at 40mph - no "high speed" runs for me!
My plan is to keep slow and check the portals every day. I will be carrying a complete set of portal inners (new) as spares. Ive done a few thousand miles in it around UK and not had any obvious problems.
Im on the point of buying some Mobilube 1 75w90 SHC fully synthetic oil for the axles and diffs. Ever come across this oil?

 

[Doug Hillary]

Hi,
frencian - Mobilube 1 SHC 75W-90 is an excellent product - I have used it over many years and many millions of kms with excellent results. Use it with confience. It has performed similarly to Castrol's Syntrax 75W-90, another excellent product

 

[m37charlie]

As Doug stated, Mobilube 1 SHC would be an excellent choice and it is on the 235.8 list, as is Mobil Delvac Synthetic Gear Oil 75W90. I think you can get the Mobilube in nice easily storable 1L containers for travelling with.

Charlie

 

[user52165]

Originally Posted By: Vikas
Where are your Unimog pictures? Isn't that the thing which climbs vertical walls???


+1

Pics or it doesn't exist.

 

[frenchian]

I filled all the portals and diffs with Mobilube 1 75w90 SHC fully synthetic oil and brought 3 litres spare with us. We developed a leak from the front right seal which is now fixed but in the process I've used quite a bit of my spare oil. I can't source this oil here (Namibia), in fact 75w90 GL5 doesn't seem to exist, the nearest I've been able to find is 80w90 GL5 (several variants) - the best looking so far is Castrol EPX 80w90 GL5 with the following specs : ZF TE-ML, 16b, 17b, 19b, 21a. Any thoughts on its suitability please?

Thanks, Ian

 

[m37charlie]

I heard about your leak on Benzworld.
I think in the absence of a 235.8 75W90 any GL5 80W90 is fine.
Actually portals don't get very hot, at least mine don't.
In my travels in Australia the hottest my rear portals got was about 45 deg F over ambient, the fronts about 30-35 deg above ambient. The diff centers got considerably warmer.
Even 85W90 or even straight 90 would be OK if nothing is available in the 75W90 or 80W90 range, as long as it is GL5.

Charlie

 

[frenchian]

Thanks Charlie, I thought as much but wanted to double-check!

I'm thinking of applying a little mod to the portals involving a couple of clutch fluid reservoirs, some pipework and some drain plugs to create what would effectively be "expansion bottles" for each portal. It's what a lot of Germans do.

Ian

 

[m37charlie]

Theoretically the front portals breathe through hoses going to the diff center which then has a breather to the atmosphere.
The pumping problem I referred to previously is though to be due to a combination of foaming and pumping action of the rotating gears.
The optimal solution is the "fix" hardware supplied by "Von" on the benzworld site.

Charlie

 

[frenchian]

I haven't been able to locate the hardware needed for my mod yet, so am continuing with the top-up every day cycle. I'm putting in on average about 60ml each side every time we do more than 150 miles.
I've still got 2 litres of the Mobilube 1 SHC 75W-90 left but am now considering reserving it for the rear portals/diffs.
I've found that Castrol EPX 80w90 is easily available (but is mineral based) - I haven't been able to determine if the Mobilube can be mixed with mineral oil - does anyone know?