Home Forums Hunting & Shooting Hunter's Campfire Didn't expect this in my oil change.

I changed the oil in my manual transmission, transfer case and rear differential today. It's a 2008 Tacoma sr5 4x4. I bought it at 8000 miles and it now has 115,000 on it 9 years later. I have never changed the drive train oil.

After I finally got the rear differential plug out ( The fill plug was a bitch) there was a tiny amount of dark sludge on the plug magnet but the rest ran out looking new. Same story on the manual transmission and transfer case.

I had figured it would be dark and burned out looking, but nope it wasn't. The only plug that had a magnet was the rear differential, Just a smidgen of chips on it. I'm sure there are some other issues with oil I'm not aware of that would mean it needs to be changed, but it looked like I could do another 115,000 on it.

I put in Mobil 1 Synthetic 75w-90 LS. I don't know if that's suppose to be changed in another 30,000 or if it is intended to run longer.

At least you have the brains to change lube. Lube is cheap, Monitoring the magnets is always smart.
And, while it's not that common, the loggers I work with do oil testing every change (200 hours). It's not free, but it's cheaper to know the engine or other parts are starting to go south, so you replace stuff BEFORE it breaks on the side of a mountain. Just one of those pays for what it costs to check the oil in a lab.
Good on you.

Actually,

That's exactly what I would expect.

I change mine every two years, usually 30,000 miles or so.

I was not aware oil wore out. In a sealed unit should it not last virtually for ever? Ed k

Not forever, but a lot longer than 30,000 miles. Although I think it is good to change it more frequently after the initial change. I changed the oil in my transfer case and both axles at 160,000. It was still in very good shape. Toyota does not recommend AT fluid be changed, EVER, at least on my 07. I think they may have changed that. But at 182,000 now I'm not touching it. There are some guys over 400,000 miles on the factory fluid. At this point I'm riding it until it fails.

No internal combustion to contaminate the gear lube, transmission fluid, etc. Should last a long damn time and stay clean.

So, does it loose viscosity? Why do they say change it? I didn't change the front differential yet, should I?

heat or water is the killer of gear oil and transmission fluid.
If you tow heavy and frequently then it needs to be changed on the owners manual severe duty schedule. My plow trucks had the auto transmission fluid ( and filter) changed yearly. Gear lube every 50k. An oil analysis is cheap insurance an runs about $25 at blackstone labs https://www.blackstone-labs.com/.
You can also get the kit from any Cummins NP shop. Just make sure you use fresh clean tubing and pull through dipstick for motor oil.

My 2009 Tacoma 4x4's got nearly 195 K on it now and the dealer has done all the lubricant changes on all the drive line components according to Toyota's maintenance schedule. So far this has been the most trouble free vehicle I've ever had, even better than my previous 1997 Tacoma which was also great. Wanna do at least 250 K with this one before I even start thinking about its replacement so proper maintenance is a high priority.

The reason they say change it is because of the heat cycles.

Moisture forms inside the gear box,in rear ends or transfer cases.

Sometimes the stuff one sees around the magnet plug is just a normal amount of filings after the gear sets have been run.

The oil is cheaper than a gear set.

I sometimes wonder about the transmission fluid no longer being changed.
Maybe because of material that the packs are made of no longer sluff off stuff except when they get overheated.

Auto transmissions are now sealed because of owner confusion about which ATF fluid is correct for their vehicle. And yeah, far to many people are too lazy to look up the correct fluid and just trust a friend's recommendation or just dump in whatever says AFT on the label.

Hot-cold cycle breaks down lubricants over time. So does condensation that forms inside. There can also be a lot of shavings from gears and parts that are not visible until a guy runs them through a filter or even a rag. Also, dirt does get inside gearboxes.

I would never let my lube go more than 30k tops, especially out here in the arid west where there is always dust in the air.

Casey

Lubricants become contaminated and performance additives become depleated.

in that sense oil products can and do 'wear out'.(attrition/deteriorate/degenerate.)

thermal stability additives, oxidation inhibitors, extreme pressure addtives,friction modifiers, etc

My truck doesn't get heavy duty. I drive 22 miles each way for work and only use 4x4 when snow is on the road. My part of Ohio is pretty damned flat, no hills to speak of. When I go to S.E. Ohio to hunt there are hills but I'm on gravel county roads and they are not that steep. Sometimes township roads that can be a bit iffy. Nothing that really challenges the truck. I don't go off road at all.

Engine oil is changed every 5000 miles. As soon as the check engine light flashes when I start it I have it changed. I have lifetime free oil changes on my truck at the dealer.

There are quite a few 45+ year old vehicles here - some older - and a 2001 Dodge/Cummins 6 speed with over 300k miles. Only one auto trans in the bunch. The level of gear lube is properly checked in the transmissions, transfer cases and diff/axles - but the lube in them has never been changed since i got them. None have broken, worn out or become noisy due to lube issues. Maybe I'm lucky.

Run Mobil One in my manual trans, transfer case and rear end on my 4 Runner...

Change it about every 100K and really don't need to, as it comes out clean also..
\
ATF, I still change that every 20K even using synthetic fluid...

even with a trans cooler on them.. I just don't trust automatics, no matter how bullet proof..


Even on Tacomas where they say don't change the trans fluid, back east in 2016, I changed
them in both of our family friends trucks...they had a drain plug, but the filler hole is buried on the
side of the trans and you need a pump to get to it.. Toyota quoted $300 to change it...

I drained it, measured how much I took out, and then put that much back into it...

no place to fill it...so I took a tube off going to the trans cooler, small funnel and slow pouring
but put the same amount of fluid back into each...$22 worth of trans fluid was a cheap investment,
compared to running the fluid hot and burning it...

My Honda, Acura and other two Toyotas, have places to drain and refill them...

They aren't really sealed. They just don't have a dipstick.

I changed the fluid (all the fluid, not just the pan) in my "sealed" Tacoma trans, diy. No big deal.

When I dropped the transfer case oil it seemed more viscus than the transmission or the rear differential. I figure that's because I rarely use it.

So what would you expect from the front differential? Should I change it?

Yeah. It probably costs less to change it than replace exploded parts. I personally would and then expect another trouble free 100,000 miles.