rear differential fluid changed in 2005 4runner (first time)

[Captsolo]

I usually have my oil serviced at the dealer or an independent shop. I have a 2005 4runner with 150,000 miles.

Today I drained the rear differential for the first time. The oil that came out looked brand new (second look it was black - but had viscosity) - and I'm wondering if one of the shops didn't change it. We found all the receipts, and they told us "no".

Anyway, drain plugs (24mm) came out easy. The dealer had only one metal gasket in stock - so replaced just one.

Filled until it just started to overflow - than put drain plug back in.:guitar2:

 

[RonJR]

Not unusual. In the absence of overheating or contamination, gear oil lasts indefinitely. Unlike engine oil, there are no combustion products to contaminate the oil, nor is the gear oil normally subjected to a lot of heat.

Which is not to say you shouldn't change it every 50,000 miles or so - it's cheap insurance to do so. But it's normal for it to look just fine.

I pulled apart the transfer case in my '94 two years ago to make some mods. At 215,000 miles and 23 years of age it looked literally brand new inside. No staining, no sludge in the bottom, nothing. I had changed the oil a couple of times over the years, but I'm just using this as an example that normally, not much goes wrong in a gear box as long as it stays sealed up and isn't abused.

 

[j4run]

If you have a 4WD, it's worth noting that the front diff holds way less oil than the rear, and the front oil will likely be much dirtier than the rear. The front plug can be very difficult to remove - be sure you can remove the fill plug before draining. Seem many (most?) people never change the diff or transfer case oil, but given the relatively long change intervals it's very inexpensive insurance, and an easy DIY job.

 

[pahaf91]

seems interesting. I did a full service on my 4runner including the front, center, and rear diff fluid. Drove it for 5-7k miles and drained it for special reasons. the fluid came out dirty (almost black) and i can see small metal shavings.

maybe its just my 4runner (2006 v6 4x4 198k)

 

[radlynx]

seems interesting. I did a full service on my 4runner including the front, center, and rear diff fluid. Drove it for 5-7k miles and drained it for special reasons. the fluid came out dirty (almost black) and i can see small metal shavings.



maybe its just my 4runner (2006 v6 4x4 198k)

Do you off-road it?

 

[pahaf91]

Do you off-road it?

very much so. Usally at least once a week.

 

[firebirdguy]

Not unusual. In the absence of overheating or contamination, gear oil lasts indefinitely. Unlike engine oil, there are no combustion products to contaminate the oil, nor is the gear oil normally subjected to a lot of heat.

just wanted to clarify some of this... gear oils do not last indefinitely, the additives break down & wear out as well as the oil itself is subjject to extreme pressures & whats called shearing occurs due to this. plus a rear diff gets very warm from just normal driving, when towing the rear can get very warm to almost hot. so while there are no combustion byproducts in gear oil, there is wear & break down that limits the life of the oil & why manufacturers have a change interval for them.

 

[bob3dsf]

just wanted to clarify some of this... gear oils do not last indefinitely, the additives break down & wear out as well as the oil itself is subjject to extreme pressures & whats called shearing occurs due to this. plus a rear diff gets very warm from just normal driving, when towing the rear can get very warm to almost hot. so while there are no combustion byproducts in gear oil, there is wear & break down that limits the life of the oil & why manufacturers have a change interval for them.

True. If a fair amount of heat wasn't involved, then diffs wouldn't have vent valves. Further, I found a video on Youtube showing what gear oil looks like inside the diff while driving. There was a transparent diff cover. The gear oil gets aerated to the point that it looked like a chocolate milkshake.

 

[firebirdguy]

True. If a fair amount of heat wasn't involved, then diffs wouldn't have vent valves. Further, I found a video on Youtube showing what gear oil looks like inside the diff while driving. There was a transparent diff cover. The gear oil gets aerated to the point that it looked like a chocolate milkshake.

yeah ive seen that vid before. gear oil goes through some pretty extreme abuse, especiallly when towing or high horsepower race cars etc.

just wanted to post accurate info that gear oil absolutely does not last indefinitely. with or without heat.

 

[62caster]

Rear diff is a fun and easy job to DIY. Good job on the OP. Keep up with it every 50k.