Engine oil specs for 3rd gen

[Troybylt]

Last time I went and tried to do something really nice for a used truck with high miles, I was rewarded with a transmission that took dump on me two days after I had it flushed.

Well there's your problem, you NEVER flush an auto trans, a series of drain and fill is fine, but once auto's get over 100k if they haven't been religiously flushed at their intervals or earlier than recommended every time (And it's possible even if they have) then the gunk you flush out and off the clutches is what was holding everything together. I learned this after I lost a high mile car to a trans flush. I hated that car anyway and am glad it's gone, me and Auto's have never gotten along, switched back to manual after that but I know MT isn't a viable or desired option for everyone.

Irregardless, Synth Oil is just fine in these trucks and highly recommended by my old 35y+ experience Toyota and ASE Certified Mechanic mentor in his experience he's never seen an engine in better condition as last as long by using Dino over Synth.

 

[amalik]

Well there's your problem, you NEVER flush an auto trans, a series of drain and fill is fine, but once auto's get over 100k if they haven't been religiously flushed at their intervals or earlier than recommended every time (And it's possible even if they have) then the gunk you flush out and off the clutches is what was holding everything together. I learned this after I lost a high mile car to a trans flush. I hated that car anyway and am glad it's gone, me and Auto's have never gotten along, switched back to manual after that but I know MT isn't a viable or desired option for everyone.

Irregardless, Synth Oil is just fine in these trucks and highly recommended by my old 35y+ experience Toyota and ASE Certified Mechanic mentor in his experience he's never seen an engine in better condition as last as long by using Dino over Synth.

I don't think this is written in stone.
[MENTION=94063]slapdappy[/MENTION] and I flushed our auto transes with 16 qts. Holding up fine so far... And I did mine when I had over 200k miles without a flush.

 

[xspsi6]

fwiw i use amsoil 10 40 signature in my 01 t4r with 137k and rotella 15 40 dino in my wifes 99 limited with 266k miles no issues thus far no leaks either and since I live in Florida where it is warmer than the northern states I use thicker oil also the higher miles on the 99 mean she needs a thicker oil for sure however if I l lived up north I would not use oils this thick.

 

[LeeMajors]

Well there's your problem, you NEVER flush an auto trans, a series of drain and fill is fine, but once auto's get over 100k if they haven't been religiously flushed at their intervals or earlier than recommended every time (And it's possible even if they have) then the gunk you flush out and off the clutches is what was holding everything together. I learned this after I lost a high mile car to a trans flush. I hated that car anyway and am glad it's gone, me and Auto's have never gotten along, switched back to manual after that but I know MT isn't a viable or desired option for everyone.

Irregardless, Synth Oil is just fine in these trucks and highly recommended by my old 35y+ experience Toyota and ASE Certified Mechanic mentor in his experience he's never seen an engine in better condition as last as long by using Dino over Synth.

Yeah, I don't think this is canon.

I had really dark red (nearly brown) trans fluid when I bought mine @155k, had it flushed passively with 12qts and have put 3k miles on it since then with no slippage or problems whatsoever. In fact, it shifts smoother than it did before.

Not saying it won't take a dump tomorrow, but there aren't any obvious trans problems rearing their head--especially in the month and a half since the flush.

 

[BlazeRunner]

"flushing" a transmission can be bad if it's a power flush, not just a fluid exchange type of flush. Some repair shops will call it a flush when it is in fact just a fluid exchange.

To stay on topic, I use mobile super 10w-30 here in AZ, temps never get below 32F, and summer has long stretches of 110F+. Also being at 260k miles seems to run a bit better with the thicker oil.

 

[slapdappy]

Veering off topic...

Well there's your problem, you NEVER flush an auto trans, a series of drain and fill is fine, but once auto's get over 100k if they haven't been religiously flushed at their intervals or earlier than recommended every time (And it's possible even if they have) then the gunk you flush out and off the clutches is what was holding everything together.

the friction material is cellulose (paper). my research (couple hours googling) tells me you are correct re friction material loss in high mileage vehicles that have not been flushed.
Everything You Need To Know About Automatic Transmission Clutch Disks
Transmission Flush, When and when not to flush transmission | MDH MOTORS
Powerflush | Best Western Transmission

Irregardless

my new favorite word.

I don't think this is written in stone.
[MENTION=94063]slapdappy[/MENTION] and I flushed our auto transes with 16 qts. Holding up fine so far... And I did mine when I had over 200k miles without a flush.

yeah.
Mine had already been machine flushed by previous owner (2nd/3rd owner) at 173,000. No idea about original owner but I'll assume it was given the classic drain and refill at recommended interval. this removes some of the old fluid and leaves most behind.
mine was shifting kinda clunky so I went ahead and did the full home depot bucket style flush last year, including dropping the pan and wiping all the grey gunk (friction material mixed with metal?) out of the pan and off the magnets (metal, duh). Cannot say if shifting improved. Thought so but may have been self delusion.
Actually re-flushed recently after using a "miracle" additive, which required driving for 4000 miles then replacing. Put "miracle" on a bottle and add a few anecdotal testimonials and I'm likely to buy in. Maybe it was detergents and friction material? No idea.
About the same time I removed the rear drive shaft and cleaned the gunk (old grease) from the sleeves and seals. Pretty simple. This most likely fixed the shift clunk (reverse to drive/drive to reverse) and hard/harsh shift 1st to 2nd.
Subsequently shifts smoother, especially first to second and drive to reverse. Not perfect but no longer clunky. Def improvement.
So, reality based advice is don't do the full flush above ????? miles.
Anecdotal experience for me and amalik is positive, but we don't know the full maintenance history of our second hand vehicles.

 

[northernT4R]

It's funny how we ended up steering towards a discussion on ATF fluids. Coincidentally, that'll be my next research project. The fluid in my '99 Auto is is dire need of replacement...

Think I'll start a new Mobil ATF thread....

 

[acr_ted]

Me...

Thanks for the info Woody - I think I'll just keep on doing what I've been doing

Next time I need filters I'll get the larger one. I usually r&r the filter through the fender flap...with the skid plate on it hard to reach from below.

Ted

 

[TheFastChef]

New Engine!

So a little over 333,333 MI and she blew a head gasket pulling my camper in Sturgis South Dakota.
I've been putting a lot of money into her, it's a 98, 3.4 Limited, from California without a spot of rust on it. So I'm putting in a brand new remanufactured long block. Although the original motor had conventional oil I'm wondering if maybe I should start this engine out with synthetic oil from the very beginning.

 

[T4R2014]

So a little over 333,333 MI and she blew a head gasket pulling my camper in Sturgis South Dakota.
I've been putting a lot of money into her, it's a 98, 3.4 Limited, from California without a spot of rust on it. So I'm putting in a brand new remanufactured long block. Although the original motor had conventional oil I'm wondering if maybe I should start this engine out with synthetic oil from the very beginning.

A failure at that mileage while pulling a camper doesn't indicate that oil had much of anything to do with this failure. Sure, synthetic is objectively better. But conventional definitely didn't hurt that 5VZ. Pick what you like. I personally use synthetic regardless of mileage.