Hi Brian,
First the oil viscosity
A comparison of several oils. Gear oil viscosities are rated at 100 degrees F. Motor oil viscosities are rated at 210 degrees F.
SAE 5W-30 would have a viscosity of 90 SUS at 100 degrees & 35 SUS at 210 degrees
SAE 30, the originally recommended oil, would have a viscosity of 480 at 100 degrees & 65 at 210 degrees.
SAE 20W-50 would have a viscosity of 300 at 100 degrees, & 100 at 210 degrees.
RL MT-90 a 75W-90 gear oil, would have a viscosity of 200 SUS at 100 degrees, & 100 at 210 degrees.
Obviously, the transmission will hopefully be operating at somewhere between the two temperature/viscosity ratings. Your 5W-30 is much thinner than the originally suggested SAE 30. Leakage in the OD pump, accumulator, valves, & servos would likely result in too low operating pressures, especially at higher temperatures. Depends on th condition of the internal parts.
Many folks have good results with a non exotic SAE 20W-50 motor oil.
Any oil that contains friction modifiers such as some of the synthetics is likely to cause slippage of some of the internal parts. The transmission synchronizers require friction to work. The two OD clutches require friction to work.
MT-90 is preferred by some because it specifically does not have friction modifiers & gives more positive synchro & OD clutch operation.
Control valve adjustment
The control valve located under a brass cap near the front RH side of the OD must be correctly adjusted. Under the brass cap is a spring, a spring follower, a control ball, & a long operating rod. The ball should be 5/16 diameter. The ball lift is what controls shifting. The book method of putting a pin through the RH arm & adjusting the LH operating arm is not a very reliable method of setting the ball lift. Wear in any of the parts will change the required setting from the original pinned arm method.
The most accurate & reliable method of setting the valve lift is:
a- Set control valve ball lift to .030" to .040". Measure with dial indicator. Cap & spring removed. Adjust clamped operating arm. Verify movement with the solenoid plunger, not the arm. I machined an adaptor to fit snugly in the plug hole & to extend high enough to provide a flat surface for a dial depth gage to sit on. I made a cup shaped end for the gage so that it would easily center on the ball.
b- Set solenoid control arm (on solenoid plunger) to .160" drop. Adjust stop or add stop below the plunger if needed to accomplish this. (Arm drop is not the same as plunger drop due to slack in lifter.)
OD operate solenoid
a- The OD soleniod is designed with two electrical coils. The first coil (operate coil) is energized by the OD circuitry. It momentarily draws about 20 amps. As soon as the solenoid is operated, a contact on top of the solenoid opens & transfers current to the second (holding) coil which draws about two amps. If the switching contacts are dirty or damaged, the solenoid will be operating on the holding coil only & will not have enough power to engage the OD. The contacts are located under the top rubber boot.
b- If the switching contacts do not open due to contact problems or the solenoid travel not being adjusted to give a full soleniod stroke, the solenoid will remain energized by the operate coil & burn out quickly.
D