Too much gear lube

marty in Ohio

marty in Ohio

Well-known member
Need some advise. After driving about 15 miles yesterday I pulled the '30 town sedan into the garage and decided to check the level in the rear axle. When I pulled the top plug the gear lube gushed out! I got it all over the floor and myself before I could get the plug back in. Next, I tried the transmission and the same thing happened. They were both filled with 600W.
Where did all that grease come from? Would it expand that much when hot?
I intend to change the lube in both, but can't figure out where it all came from.
Marty
 
Apparently both the trans and rear end were overfilled when they added oil.

Just let the oil flow out untill it levels itself to the bottom of the plug. Then, the next time you check you will not see it gush out. You then would place your finger inside the hole to see if you have oil at the bottom of the hole.
 
Old31. Thanks for your reply. I can see hoe a transmission could be overfilled if you had the top of the box off and put the lube in. But, the real axle will only hold enough to reach the fill plug. I'm stumped.
Marty
 
More important to monitor the lube level in the transmission as if the seal at the front of the drive shaft is bad, lube will seep down to the rear, over filling it.

If the rear axle is too full, it could leak past the outer axle seals, eventually soaking your rear brakes. Be aware and keep an eye on lube levels.

Lastly there is a factory vent hole in the shifter tower. Make sure that is open.

All above are 'worst case', as I suspect your trans & rear where over filled.
 
Oil can flow down the torque tube from the trans to the rear end. Definitely keep an eye on it cause like others are saying, it can leak out and coat your rear brakes
 
I don't know the OP's history with the car but I will add another possibility. In floods, the flood water will seep in where it will settle to the bottom since water is heavier than the oil. a person can only find out if water is in there by either the milk shake check immediately after driving the car or by pulling the drain plug to see if water comes out. If the car has set for a while after the last drive, the water will come out first and be obvious that it isn't lubricant. Hopefully, it is all lubricant since water can get acidic over time and damage the gears & bearings.
 
Drain the rear end and transmission and refill with 85-140 G5 gear oil. Check the levels again after 100 miles.
 
Thanks all for the responses. My history. I've owned this car for more than 30 years and have done most all maintenance myself. I keep an eye on the levels and this is the first time I've ever seen the gear lube come out of the filler port. I'm wondering if this is because I checked the levels when the car was hot. I know liquids expand when hot, but this seems excessive. I understand that the lube from the transmission can travel down the drive shaft tube and end up in the rear axle, but I would think then that the transmission level would be low.
Marty
 
If you let the car cool down before checking levels, you will lessen the chance of burning yourself on the muffler.
 
If you let the car cool down before checking levels, you will lessen the chance of burning yourself on the muffler.


Boy don't I know that.
Marty
 
Hello, could be the oil was splashed on sides of transmission and axle assembly, and was still setting down, if refilled at that time would then be overfilled.
 
Marty and others, if you fill with cold oils you can overfill, the level will be higher as your filling and then the oil starts to come out you quickly install the plug so you don’t make a mess. I did this to grandsons 1/4 midget engine, at the race his engine was doggy, drained the oil and refilled keeping the level just below the opening, the engine was noticeably snappier ! happier !
 
Does your oil look foamy at all? Air in the oil will increase the level.

I was having an issue with 600W foaming in my transmission. I switched to Lucas 85w-150. Problem solved.
 
FINAL OUTCOME. When I pulled the top plug on the transmission and the rear axle this cool morning, the fluid levels were right where they should be. As long as I was under the car I changed the lube in both.
I guess I learned to let the car cool down before I jumped in with my wrench.
Thanks for all your replies.
Marty
 
Maybe there was foam in the oil that diminished when the oil cooled down. Y-Blockhead said that some 600W oil foams (post #14). I have had the best luck with modern gear lube (85W-140 G5). It has additives that will reduce the wear in your gearbox and rear end.
 
Last edited:
nkaminar said:
Maybe there was foam in the oil that diminished when the oil cooled down. Y-Blockhead said that some 600W oil foams (post #14). I have had the best luck with modern gear lube (85W-140 G5). It has additives that will reduce the wear in you gearbox and rear end.
Click to expand...

I have been using 600W in gearbox and differential. I just switched both to 85-140 GL5 and so far have noticed no difference. Proof will come this winter, the car has always been very difficult to shift the first mile or so from a cold start. I hope the new lube improves things. And yes, I realize that in the SF Bay Area we don’t really know cold…
 
A lot of the "600W" lubes that are sold by vendors are not the original steam cylinder oil. They are mixtures of gear lube and viscosity builders such as STP oil treatment. Blended gear lubes of the GL1, GL4, or GL5 will have anti corrosion and anti foaming additives blended in per the ASTM or ISO standards. Stuff that is made up in the back room of some vendor's shop will have less of what there should be in there.

A person can use a straight grade SAE 140 gear lube and have something that is comparable in viscosity but will be superior in gear protection.
 
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