From 5W-30 to 0W-20

Idk man I've damn near overheated twice.

I think when Toyota says "extreme load conditions" it includes bolting on some 34" tires and wheeling for 8 hours straight in 120 degree weather. Seeing coolant temps of 235+... nearly boiling over.

The other time was in the California desert. Going 80+ mph on the highway, hauling a few hundred lbs of gear. 115F degrees outside... on a slight uphill for a couple hours. Coolant temp was over 230.

I consider these to be extreme load conditions.

 

Been running 5/30 for six years and 50k and it’s still going.

 

5/30 sure makes the engine sound quieter

 

230F is hot- imagine tranny temp! Perhaps new engine oil and new tranny ATF after a hot extreme load trip would be a good idea.

 

Tranny temp was over 245 at the converter when wheeling in palo duro canyon that time. Did a flush when I got home.
I'll be adding some additional cooling soon.

 

I’d agree, especially since when toyota uses the word “severe” to define service intervals, it’s what most people do normally.

So when they use the word “extreme load conditions”, I would definitely interpret it to mean anything that is not a stock, empty 4runner driving on flat ground at 55mph.

While I run 0w30, I’ll admit I do change to 0w20 in winter, just because of how damn cold winters can get here.

 

Here is an interesting list of temperature and life of fluid that seems relevant here.

 

I’m pretty sure those numbers are from a very out-of-date infographic but don’t come after me if I turn out to be completely wrong.

 

Alright here's the thing guys. Do we need another oil debate thread?! We've already veered off topic (sorry)

I propose we all just shift the conversation to transmission fluid because that will fail before the 1GR-FE does... Especially if you stay on top of oil changes.

So, with this proposition out there... I was thinking about adding a Hayden 678 transmission cooler. Only problem is I'm not sure if it's quite big enough.

A few companies making brackets for it as well. Looks like a very easy install.
https://goliathoffroad.com/products/4-runner-transmission-cooler-bracket?variant=49409409646839

Anyone with experience of running a cooler that does not require AN lines?

 

AN lines?

 

Some coolers use AN (ARMY/NAVY) fittings and lines.

While this would be cool it adds some additional cost and complexity. The factory system uses hard lines and rubber hose. I'd prefer just using some rubber hose and hose clamps. Just me being lazy really.


Note to the mods: If this topic change annoys you please delete.
It would be better suited here anyways
https://www.4runners.com/threads/5th-gen-trans-cooler.11238/page-2

 

Any cooler over nothing is big enough. In all my years owning a Toyota product with this trans, I have never seen one throw an overtemp light and that was after many, many supercharged 4wd launches in my Tacoma.

Looks like your link copied these guys:

https://iconicfabricationoffroad.com/products/2010-4runner-transmission-cooler-bracket-kit

 

Sure enough, looks about the same.

I’ve decided to get buy a

$65 Derale 13504 Series 8000 Plate and Fin Transmission Oil Cooler , Black

Derale 13504 cooler. It’s quite a bit bigger and should provide some serious cooling.

Should be prepared for the Texas heat real soon.

If I keep experiencing engine heat trouble I may consider a CSF radiator as well. But for now I’m more concerned with the transmission temps.

 

Is it very dusty where you wheel? And have you ever cleaned the radiator? Maybe think about the fan clutch too, I think that's an easy test.

I'm sure it's hot as fuck down there, and that's probably the main problem, but it wouldn't hurt to make sure every part of the cooling system is working at its best.

 

And I don't know what speeds you're running at, and you've probably already done this, but I'd try dropping into low range / limiting the trans to a lower gear to let the engine rev higher. My 4R will drop temps significantly when dropping a gear, even when speed seems "fine" for the current gear.

 

I should definitely clean it although I doubt that's the problem since during normal driving on the street it has no trouble staying cool. Over 110 degrees outside and slow wheeling I see temps start going up. There's just no airflow at this speed.

I will say, it wasn't just me. Everyone with some sort of scan gauge or monitoring system was watching coolant and trans temp climb.

For wheeling I'm in 4lo S1 or S2.
For gear hauling I leave it in 2hi. If I start gear hunting I'll keep it in S4 which helps tame transmission temp.

Honestly I think its normal operation. I'll add a trans cooler cause it's cheap and easy to do.

On the road (even in tx summer heat) it's not often I see coolant temps climb like that. But... Death valley is named appropriately.

 

The reason the oil keeps getting thinner is it reduces pumping loss because a syrup oil is harder to pump than a watery oil and that affects fuel economy. When in doubt, follow the owners manual (unless they claim it's a lifetime fluid).

If I owned a car where the manufacture suggested a heavier oil for the same engine when they didn't have fuel economy standards to meet I'd go with the heavier oil because why would they suggest a heavier oil if it had no advantage? Everyone wants better fuel economy, they wouldn't forgo it if there was 0 drawback to using lighter oils. In very cold climates, I'd use the lighter oil if instructed.

Air cooled engines also use heavier oils because they're normally operating at higher temperatures because air cooling is less effective. My Honda XR used 10W40, and when I'd check the oil after hard use it was not a 40 weight oil, it was more like 20 or 10 weight. So if you start off with an oil that's already light, you'd have no protection once you got up to temperature because the heat is so great.

 

Another consideration is fuel contamination.
Some fuel and carbon will always leach past your piston rings and get into you oiling system. This is why oil turns black. And too much fuel mixed with the oil is problematic because 1. It displaces oil. and 2. it changes the viscosity of the oil.
This is why I'm an advocate of frequent oil changes. Regardless of oil type.

Now, if you're in an area that doesn't get very cold but the summers are very hot, I'd consider moving toward a heavier weight. Especially if you operator the vehicle under what you'd consider "extreme load or high speeds"... Although these are Toyota's words directly from the manual I believe they are purposefully ambiguous.

Granted, most engine wear will occur during a cold start, so that's the trade off. 0w-20 will arguably be a better oil for this. So if you're the type of person to make short trips and never really get the system very hot 0W-20 and frequent oil changes will probably be the best bet.

On the other hand, if you are the type of person to "cold start" your rig when it's 90F outside, then proceed to drive through a desert or go wheeling for hours straight, I really do think a heavier weight is a good option for you.

Regardless, the heart of your post is correct... heat is a real killer. Oil contamination will happen so frequent oil changes help a ton. But any fluid exposed to heat will start to break down. This is why I choose 5w-30 for my summer climate, and 0w-20 for winter. Change the oil every 5k miles, and transmission flush every 50k (or every time it goes over 230F)