call me stupid...

[jonny80stry3]

Thoughts on changing diff and transfer case oil after running in 4H at 60-65mph for 1.5hrs. Figured if you can shift at 50.... 60-65 should be fine.

I've read the other threads concerning 4H speed thresholds, there doesn't seem to be a consensus.... beyond running at that speed is stupid....

F...er was hot when I arrived at my destination. Just worried oils may have broken down with that much heat.

Everything seems fine.

Reason for doing so: freezing rain while traveling 91N Nh/Vt border. Plenty of cars off the road and a decent tractor trailer pile-up that day. 4Runner handled it great.

2018, 9k miles.

 

[nb rob]

I’ve travelled at interstate speeds lots in 4hi.
You’re over thinking it. I’ve seen limiteds trying to break the sound barrier on the interstate. There’s not much difference in their driveline except for the Torsen center diff.

It’s much preferred over being that guy driving in rwd on the slippery highway putting everyone’s lives at risk.

 

[T4R2014]

Yeah dude, car shit gets hot when you use it. Everything except the AC. You're fine.

 

[Pathfinder!]

You may be an idiot,I don't know you, but your truck is fine.

 

[CavPro]

Yeah dude, car shit gets hot when you use it. Everything except the AC. You're fine.

The other side of that system gets very hot, so yeah, everything gets hot.

 

[Industrialwrench]

Your thought process is spot on. Temperature, time, and emulsified water are the things that breakdown oil. Freezing ambient temps are going to help. High temp breakdown is going to take much longer than an hour at temps below 230*. You’re fine. If you do this all the time, you should increase the service intervals.

 

[osugsxr]

Geez , I change mine every time I do 75mph in 4hi just to be safe.

 

[T4R2014]

The other side of that system gets very hot, so yeah, everything gets hot.

Layman's terms. He already wasn't familiar with a part-time transfer case.

 

[1000MPH]

Geez , I change mine every time I do 75mph in 4hi just to be safe.

The Toyota Warranty and Maintenance Guide practically says that...

In addition to the maintenance items indicated for each mileage/month interval, you should perform certain inspections daily when you drive off-road. Whenever you take your vehicle off-road through deep sand, mud or water, perform these inspections every day:
• Check ball joints and dust covers
• Check brake lines and hoses
• Check brake pads/discs
• Check differential oil
• Check drive shaft boots
• Check engine air filter
• Check nuts and bolts on chassis and body
• Check steering linkage and boots
• Check transfer case oil (4WD models)
• Check transmission fluid or oil
• Lubricate propeller shaft​

 

[Ghostrider]

Geez , I change mine every time I do 75mph in 4hi just to be safe.

First reading I thought you said you changed it AT 75mph. That would be impressive

 

[Akkording]

It's a 2018! Just drive the heck out of it, you will be fine bud.

 

[osugsxr]

The Toyota Warranty and Maintenance Guide practically says that...

In addition to the maintenance items indicated for each mileage/month interval, you should perform certain inspections daily when you drive off-road. Whenever you take your vehicle off-road through deep sand, mud or water, perform these inspections every day:
• Check ball joints and dust covers
• Check brake lines and hoses
• Check brake pads/discs
• Check differential oil
• Check drive shaft boots
• Check engine air filter
• Check nuts and bolts on chassis and body
• Check steering linkage and boots
• Check transfer case oil (4WD models)
• Check transmission fluid or oil
• Lubricate propeller shaft​

Don’t forget the horn

 

[CutthroatSlam]

Don’t forget the horn

Also, don’t forget to check the floor mats