Synthetic or regular ear end oil 140w?!

[busfan]

In 1962 fishbowl manual it says to use 140W  year round and to use 90W below 0.

I am familiar with one thread that goes on at length about this topic and says to use Delvac Synthetic 50W trans fluid in the rear end instead.

Also says to use gl4 50w in the 4spd spicer gearbox.

Thoughts?

No quiero leaks!

Thanks!

[chessie4905]

We used Lubrication Engineers synthetic 140w gear oil in our 4104.

[bevans6]

If it has a typical hypoid gear in the rear end, always use a proper gear oil, never use a transmission oil.  GL-5 is best for differentials, GL-4 can be used in transaxles like VW Beetle where the same oil is used in the differential and the transmission.  MT-1 oil is intended for manual transmissions and bevel gears.  In your case, I would probably use a 90W-140 plain, or if money was flush, a full synthetic.  They are compatible and can be topped up.

Good summary;  https://en.wikipedia.org/wiki/Gear_oil

Brian

[buswarrior]

Differentials are in need of serious and proper lubrication. The lube must be able to withstand the forces involved.

Shear maybe? (I really miss the engineers that used to be on the Boards...)

Anyway, stick to a proper gear oil.

happy coaching!
buswarrior

[busfan]

Thanks all! Just realized I posted ear end oil  lol.. Appreciate the gear oil fortifications, I was looking at this link. http://www.busconversions.com/bbs/index.php?action=printpage;topic=22824.0

Anyway Wont be driving it much distance till I can get a look and paint the teeth, going with the thick stuff

[bevans6]

I see I featured in that thread too!     I think the final answer would be that if it's rated GL4 or GL5, it can be used in a hypoid gear differential.  Lots of oils carry multiple ratings, so just go by what's on the label.  MT-1 for transmissions, GL-4 for both transmissions and differentials, GL-5 for heavy duty use in just differentials not transmissions.

[Oonrahnjay]

Differentials are in need of serious and proper lubrication. The lube must be able to withstand the forces involved.

Shear maybe? (I really miss the engineers that used to be on the Boards...)
Anyway, stick to a proper gear oil.

happy coaching!  buswarrior 

   Shear but (for especially for a gear oil), "extreme pressure" -- that's why you'll often see a rating 90W-140 EP.  It's called that because the pressures of the teeth rubbing together and the loads on bearings, etc. are extreme.  Gear oils are different - run the wrong oil in your car engine and your rings or lifters might be worn in 100,000 miles; run 700 miles with the teeth forcing the oil out so that you have metal to metal contact and you have a gears that are starting to shed teeth.  That's not too good.  And it's expensive.
   And, yeah, me too.

[dtcerrato]

Lucas 85/140 WT here since 2000. Quiet with no issues.

[busfan]

Thanks all!  Appreciate the insight, now for the 4 speed GMC transmission..

Manual says use the oil weight your using in the engine.

Ok to go delo 400 instead of 2 cycle low ash? 

I Was changing the GMC / Spicer Vd and decided to go prospecting for metal with my telescoping magnet with a rare earth dime size extra on the end, man I must have pulled 5 small grape size very fine of metal globs out the bottom right corner :| Been a long time I guess!

Is consensus 50w here in a 4 speed 1968'ish 4 speed?

Mainly ambient temp dependent?

[bevans6]

I used the SAE 50 synthetic MT/GL4 oil we were discussing above, in my Spicer.  Transmissions don't need the additives, detergents, etc that are in most engine oils (except, to some degree, the straight weight two stroke diesel oil we use in the big green leaker).  The do like anti-foaming additives that aren't in engine oil.

[dtcerrato]

50 wt non detergent aviation grade oil in the 4 speed Spicer is what the lube chart call for (at least in the 4104 maintenance manual). The late "Deans Coach" recommended a full synthetic in the Spicer soooo about 15 to 18 years ago we started running Shell Dentax (no longer available) which was a synthetic superior upgrade for Spicer lubricant for both longevity of service (500,000 mile change interval) and consistent viscosity across the full temperature spectrum. We have the same batch in it from that long ago - and oh yes the gears grind less...

[busfan]

Thanks !