Spicer Four Speed Lubricant

[Fredward]

What are we supposed to be running in the spicer 4 speed manual tranny? MC-5.

Thanks,
Fred

[Tony LEE]

Engine oil

[gumpy]

I think 90Wt gear lube is what was used in the MC8 I had.

[tekebird]

Again

Step one: Buy a Bus

Step two: buy the manual for it.

[Ncbob]

Or listen to the folks who've been there, Doug.

Fred, I've mentioned this in earlier posts but will be happy to do it again.  My MC5A must not have had the transmission oil changed in eons and that was on my mind when I pulled the engine to do the clutch and install the Jake Brakes. Da Book calls for the same oil as in the engine, SAE 40. Having driven the bus home from IL I wasn't a happy camper with the shifting and it appeared to me that it was a bit more difficult the more highway I saw behind me.

For the record, I'm an 'Old' double clutcher from back in the late 40's when I learned to drive the farm trucks. Too, I had to replace the transmission input shaft (it was too sloppy where it mated to the next shaft) so I opted for an oil I felt would be a bit heavier and more lubricity than standard engine oil. I put in Valvoline 50# Racing oil (available at Advance Auto) and haven't had a squawk since. Granted we only run the warmer climates so that might make a difference in your decision...but for my tastes...it wouldn't make a shadow of a difference.

Your choice...just my experience.

NCbob

[Tim Bookmiller]

Fred,
On my last trans. oil change I of used 40 wt engine oil with a 30% mixture of Lucas oil treatment and it seemed to make trans shift a little easier and stopped real seal leak.     

[FloridaCliff]

I am using Delo 40wt.

But on the next change I am going to try out the 50wt like NCBob has done.

Bob has had positive results with his own actual driving tests by going to a heavier wt oil.

And nothing like real world results vs theoretical results.

Cliff

[Dreamscape]

I use the same 40 wt oil as described in the manual.

Ncbob brings up a good point using 50 wt.

Another good point is using Lucas. I use that in the engine, guess it sure couldn't hurt using it in the transmission. Anybody used that with the 50 wt?

Paul

[Fredward]

Thanks guys. By the way I have the manual; I'm just wondering what really works. I don't always go with what the manual says. 
Fred

[gus]

Fred,

Just curious. What does the MCI manual say to use?  I assume both buses use the same trans since the drive lines are so similar.

My 4104 manual says to use 50W aircraft grade mineral oil. I just happen to have some 50W aircraft engine break-in oil which is mineral oil so I use that.

This Spicer 4-sp is not supposed to use 90W because it has an oil pump, it is not the usual type trans used in later years. GMC used these same trans on their heavy trucks in the '50s, I have four of them.

[RJ]

Fred -

Some folk have used straight 40wt synthetic oil in their manual transmissions, with reportedly good results.

FWIW & HTH. . .

[tekebird]

problem is with synthetic is that if you have a leak synthetic will leak at a higher rate

[DavidInWilmNC]

Out of curiosity, what's the oil capacity of this transmission?  A transmission oil change is on my fall / winter to-do list and I'd like to know how much to have on hand and how much to expect to have to contain when I drain it.  I haven't been able to find this in my manuals.  I'll probably go with the 50 wt to see if it helps it shift a bit smoother.  When it's cold, it shifts no nicely.  After a few miles, it (or I) have problems with those damned gear crunches.

David

[Dallas]

Out of curiosity, what's the oil capacity of this transmission?  A transmission oil change is on my fall / winter to-do list and I'd like to know how much to have on hand and how much to expect to have to contain when I drain it.  I haven't been able to find this in my manuals.  I'll probably go with the 50 wt to see if it helps it shift a bit smoother.  When it's cold, it shifts no nicely.  After a few miles, it (or I) have problems with those damned gear crunches.

David

David,
I'm not sure how much your transmission holds, but to help with the shifting problem after the transmission warms up try letting your rpm's drop longer than you think they should.
It takes quite a while for a Detroit to lose 500-600 rpm.
Instead of counting 1-2-3 like you would with a car or truck, count 1-2-3, 4-5-6 before pulling your shifter back into gear.

IHTH
Dallas

[DavidInWilmNC]

That's the one bad thing about converting this thing; I can't just go out for a spin in it!  There are so many tools and parts lying about.  At some point, farther down the road, I'll get to practice more, which is exactly what I need.  I'll try giving it a bit more time, especially the 1-2 (and the 2-3 and the 3-4  ) shifts.

David