Opinions on Differential Oil Froth

Hey,

I just changed the rear diff oil in both my Tundra and 4runner. I drove each of them a few miles before draining. The 4runner was pretty dark but looked like oil. The Tundra looked all frothy and goo like. See pic. General consensus of the internet is that the froth is normal. I'm not too concerned, just curious if the tundra fluid may have had an additive or maybe they were different oil types. Considering there's not much else going on, what do you think?

 

never seen that before. Mine was pretty clean. Normally water makes thAt milky color ? I would guess water?

 

Me too.

 

I should clarify that what I read on the whole entire internet is that bubbly fluid is fine. This seems more Frothy to me. How would water get in the differential? Condensation?

 

Mine was pretty clean when I changed mine. I agree, that this looks like water. Maybe rear axle seals. Not sure.

 

That's emulsified oil. Condensation would be a cause if your truck sits a lot and when it does get driven it is for short trips. Other than that water has entered via the vent some how.

You would have an oil leak if the axle seals are shot.

 

This^^^
Water emulsified in the oil.

My 07 looked nothing like that just used gear oil.

 

@thearborbarber I'm not sure how the truck was used prior to my purchase of it about 2000 miles ago. I drive it daily 32 miles. I did read elsewhere now that a clogged breather could prevent condensation from escaping. I think this fluid had been changed before, but likely not on the runner. Seems like I need to change the Tundra' again in a few thousand miles just to be sure the old stuff is all out.

 

Personally, I'd replace the breather (relocate it while you're at it) and change the fluid in a week or two. I wouldn't feel comfortable leaving it for several thousand miles. That's just me. Three bottles of gear oil are far cheaper than a differential.

 

Excellent idea. Replacing the breather is cheap too.

 

If the breather sticks it will blow out a seal. My guess is that the previous owner drove through water. If it was me (if it's 4wd) I would change the transfer case and front diff oil as well. Also grease all of the u-joints. Most likely is the rear diff was warm and then got wet. That will cause the warm air in the diff to contract. If underwater the diff can pull in a small amount of water each time. It's not just flooded roads or playing in the mud. If the previous owner had a boat each time he pulled the boat to the launch he would of heated up the rear diff more than normal (since he was towing) and then backed into the water (in which case the front diff and t-case should be fine). Good you caught it now. I would also use cheap gear oil and change it again in a couple hundred miles with good stuff to make sure to get as much out as possible.

 

Whoa, definitely relocate the rear breather