gear and tranny fluids- what to use

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IdahoDoug said:
I've been on a plan like Raven's since new. I drained/filled the 6 qts available via the drain at around 30k (442). Then at 75k I had the pan dropped and professionally cleaned/refilled the old fashioned way (no flush, etc). From then on, I drain 6 quarts annually and fill with Chevron DIII. My tranny shifts smoothly whether I'm around town or yanking the 6000lb boat trailer - like new, really.

Sometime around 200k, I'll have the pan dropped and the filter cleaned again (currently around 140k). I got this from years of asking cab drivers how their company takes care of their vehicles. They simply drain monthly and never have any tranny issues even on GM trannies in the 300k range used in stop/go traffic. From this, I concluded that having fresh clean fluid in there is the way to have a lifetime tranny. Also agree not to flush an old tranny with poor maintenance. Lots of tiny orifices and valves in there that could get clogged by blasting loose grundge all at once. Better to dissolve it over time as Raven described.

DougM
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Glad to hear some long term feedback on that method even if for a diffrent tranny they are both toyota tranmissions behind a 1Fz :)
 
Yup, I'm with Doug I run M1 and change it way more often than is necessary, I change my front diff at least once every year. The cost is like $20, but the feeling you get when you see yellow oil coming out is priceless.. :)
 
I was reading this thread trying to figure out what folks are using in their front and rear diffs. IIRC, Toyota specs 90W GL-5 gear oil for the diffs in temps above zero and 80W90 for below zero.

I've been unable to find suitable 90W at any local suppliers. (NAPA has 90W but it's GL-1, not GL-5) I've seen that a lot of forum members mention running M1 in the diffs - is that M1 75W90 or have you found 90W M1 somewhere. If 75W90, what is the rationale for going lighter than the Toyota specifications? Might that cause damage to the diffs?
 
People are using 75w-90. SAE 90 gear oil and 75w-90 are the same thickness at operating tempurature, the 75w oil just flows better at lower temps.
 
I just ran into this same problem. I couldn't find 90, only 80w90. I ended up putting Vavoline Durablend Semi-synth-- only half the cost of synthetic, with none of the beneifts. Or something like that :)

Anyway, it is winter, so I didn't really worry about it for right now-- but I am not sure about summer time. I am in Arizona, land of 110 degree summers.

Could 80w90 in the diffs cause a problem then? Is there any downside to 80w90? If not, then why did Toyota go to the trouble of specifying 90 for above zero and 80w90 for below zero?

Jared
 
sjpitts said:
Could 80w90 in the diffs cause a problem then? Is there any downside to 80w90? If not, then why did Toyota go to the trouble of specifying 90 for above zero and 80w90 for below zero?
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I'm wondering the exact same thing.
 
Most likely the Toyota spec is the same one they have used for 30+ years and has never been updated. In the really old days, multi weight oils could shear down and cause problems, not an issue anymore.
 
Changing the Tranny to Synthetic

I changed my diffs and t-case to synthetic Mobil 1. I would like to change the tranny over but I cannot find anyone to do it. Not even a flush and replace it with synthetic. I am in Utah, anyone know of a place.
 
ryankalel said:
I changed my diffs and t-case to synthetic Mobil 1. I would like to change the tranny over but I cannot find anyone to do it. Not even a flush and replace it with synthetic. I am in Utah, anyone know of a place.
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Your garage. It is very easy. Get 10 quarts of ATF and a tranny drain plug washer. Pull the tranny drain plug (with a large oil pan under), let the old ATF drain out, put the plug back in with the new washer and refill. The tranny will take between 4-8 quarts depending on how long it drained. Follow the factory proceedure for checking the ATF leve (cycle from drive to reverse and back with the engine running and check in nuetral). Repeat the whole procedure every 15,000-30,000 miles. Takes about an hour.
 
I have been told that the best way to make sure that everything is changed over to synthetic is to have it flushed and by doing it this way I do not get all of the fluid out. Is there anything else that I should do to make sure I get all of it out? thanks and sorry for distracting the tread
 
ryankalel said:
I have been told that the best way to make sure that everything is changed over to synthetic is to have it flushed and by doing it this way I do not get all of the fluid out. Is there anything else that I should do to make sure I get all of it out? thanks and sorry for distracting the tread
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Ryankalel,

You are correct, a drain and fill regimine will take 8+ cycles to approach 99% full synthetic. At 20k intervals you will take 160k miles. There have been a few posts describing a DIY process where a tranny cooler line is disconnected and old fluid is flushed while new fluid is added. Please read the archive posts on this as the procedure requires some careful monitoring of fluid level and I don't recall the details.

-B-
 
I am not a fan of flushing and would not recommed it. Mineral and synth fluids are fully compatible so I would recommend just doing a drain and refill. The idea of changing is to replace the additive package which is depleted over time. Even thought the two oils will be mixed the change will replace the additive package and give you better cold weather shifting as the mixed oils will have better low temp properties than just mineral oil.
 
Doug and Raven talked about intervals for the transmission, but how often (mileage or time wise) are you folks changing your transfer and diffs?
 
I use the cheap stuff (80w90) in five gallon buckets and change them with every oil change (basically all of my drive train fluids get swapped out at oil changes).

Or, if I go wheeling under harsh conditions, I'll swap the stuff out when I get back.

This--to me--is cheap insurance.
-o-
 
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