I want to replace all gear oils with synthetic gear oil
any one have any good word on it .?

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Rediscovering what has been forgotten by many
the slant 6

Just use GL-4 90 weight conventional... most gear oil is hypoid for use in rear ends not in transmissions so you have to watch it or you'll have issues getting it into gear during shifting. Some people have used non-detergent 30 weight oil....I'm not sure if they make a 30 weight synthetic without detergents....

Your option may be Redline MT 90 if going synthetic.

If everything is working fine, leave it.

That being said if you decide to do this, you'll have to pull the transmission to drain it on an A-833OD since it doesn't have a drain plug, and if you are going to washout any vestiges of conventional oil out of the case, you'll need to pull the side cover, at which point you'll need to review the fun service procedure for getting the side plate to seat properly on reinstallation... at which time, it might be best to overhaul it and get new synchros put in.

The later A833OD used automatic transmission fluid.

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If it was easy, everybody would be doing it.

In the A 833 OD in the '83 D150 I have ran: ATF, Red Line MTL and Red Line MT-90

The shifting was certainly satisfactory with either ATF or MTL,, I felt they were very comparable, nothing bad, certainly functional.

I switched to Red Line MT-90 earlier this spring, with the MT-90 the shifting is really nice, not a huge difference as it was not bad before,, it is just really smooth with the MT-90. Seems that this A 833 like the higher viscosity of the MT-90.

and the A 833 OD in the 83 D150 has a drain plug.

here is some Red Line product info on MTL and MT-90

https://www.redlineoil.com/content/file ... 20Info.pdf

Yes the 1976 forward FSM does say that. I have a mainshaft that has a galled nose because ATF just doesn't stick around on the parts if the vehicle sits for a while (previous owner was an occasional driver, but drove it hard when they did drive it)...so I go back to 90 wt GL-4... which has provided good firm shifts and only is "stiff" in the morning if the temp is below 32, but after a few minutes of motivation it gets easier, and hasn't let me down during a drag race (the clutch usually does that...)

One of our local mopar 'experts' stated that sometime in the early 70's the switch to ATF was stated in a TSB and later adopted, to provide better cold weather shifting...

Use a 75w-90 GL4 for those cold mornings........

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Ed
64 Valiant 225 / 904 / 42:1 manual steering / 9" drum brakes

Our 85 does also. Honestly,I never saw one without one. Learn something new every day.

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2 Mopars come with Spark plug tubes. One is a world class, racing machine. The other is a 426 CI. boat anchor!

12.70 @ 104.6

Red Line MT-90 worked rather well in the A833 in which I tried it. The rear axle will use 75W-90 happily or 75W-140 if you're towing in hot weather.

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Joshua

Red line seems like a great choice
I see the Forum members know what best for my old Dodge

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Rediscovering what has been forgotten by many
the slant 6

I ran a mix of DexronII & gear oil in My A833 looong time ago, no problems
& could slam thru them like lightning. Don't ask for the ratio or gear lube
weight now,...lol, too much time in the rear view mirror!!