I am going to change the oil in my 5spd manual transmission and rear differential. According to my Haynes manual it calls for 75w-90. I have had my truck for going on 2 years and I have never changed the oil so I assume it just had regular oil. I am planning on using some type of synthetic, will I run ino any issues from changing to synthetic?

The next question is what brand should I use?
1. Mobil 1 $70 for 12 qt. case
2. Amsoil Synthetic $90 for a 12 qt. case
3. Amsoil Series 2000 $110 for 12 qt. case
4. Royal Purple $100 for 12 qt. case

 

I owned a '98 LTD, and used Mobil 1 synthetic ATF and 75w-90 gear lube with excellent results until I traded the truck for a 4th gen @ 5 years/75K miles, including lots of miles towing a 4,.000# trailer. I've been a Mobil 1 fan for the past 20 years, and have no regrets.

I suspect you'll find that opinions on this issue are like bellybuttons - everyone has one!

 

I use the Mobil 1 in all of mine.

 

I use AMSOIL in everything.

Gadget

www.GadgetOnline.com

 

What's important is that it gets changed.

A seasoned mechanic once told me "The Best Oil Is Clean Oil".

This applies to transmissions & differentails units as well.

Pick a color - it really doesn't matter. Be sure the specs. line up with what's in the owners manual. Do that and any color will work fine.

 

I use Mobil 1
I haven't had a chance to try out Amsoil, but I am happy with Mobil 1 so there is no reason to change.

 

I use Mobil 1 in everything.
I seriously thought about switching to Amsoil. But if for some reason I crack or break something holding a vital fluid, I don't want to have to wait for Amsoil to arrive in the mail. I can go to any auto parts store and buy Mobil1 off the shelf. That's my only argument. Amsoil may be better, but Mobil1 is faster

 

i am about to change my m/t oil and my rear diff oil... also might do the steering box eventhough its manual steering......

from what i have read, i need gl-4 and gl-5

what wieght for everything?

or does it not matter? from what i remember, gl5 is just a thicker viscosity, but i have never seen gl4 anything in hte stores... only gl5 in numerous multi-wieghts......

 

I use Mobil1 in the engine, dyno everywhere else since I haven't found a place that stocks the gear oil & tranny fluid from Mobil1 yet. I get everything changed every 5k miles (tranny @ 15k) so I'm not worried about it.

 

around here, they have mobil 1 gl5 gear oil in assorted weights....

i have the toyota manual for 1985 and it isnt specifeid, in some sections it will say GL-5, SAE 90 so is that gl-5 or straight 90w that meets gl5 specs?

also what wieght is gl4? i cant find it anywhere.....

 

Have never seen the "gl-x"spec, but if it calls for 90 weight, use that. the "gl" spec might be the Japanese or European equivalent of SAE.

 

the GL-x spec is from the API American Petroleum Institute.....

one of the listings in my manual actuallly says "API GL-5, SAE 90" now are these the same or what? and also, from what i have gathered GL-4 is thinner than gl-5, so would that equate to like straight SAE 80? or what?

 

GL stands for "Gear Lube". It's an SAE specification for the nature of the additives in the gear lube. GL1 through 5, with 1 having nothing, and GL5 having the most. This is similar to the S_ designations for engine oil btw.

GL5 oils have hypoid additives to deal with the extreme sheer stress of...hypoid gears (differentials). The additive of concern is sulfur, which is what gives it that special stink. Sulfur is detramental to yellow metals. It's also very slippery. In the Toyota transmission use of a GL5 oil leads to problems with shifting, and may lead to failure of the synchro's as a result.

GL4 and lower oils can be found at agriculture supply stores, albet generally in 5 gallon buckets. Sometimes Walmarts carry this oil as well.

You can probably use an engine oil just fine in the gearbox. I haven't done this in a Toyota truck gearbox, but I have in many other gearboxes without problem. Particularly those gearboxes that very much have to avoid GL5 type oils. Straight weight 30 should do just fine. 10-30 would keep you from having the interesting stiff shifting on cold mornings, and could gain you a smidge of power and mileage from reducing parasitic loss.

 

um, my toyota manual says to use gl5 in the tranny and the rear diff

and it says ule gl4 in the steering box......

now, are you sating i shouldnt use gl5 in hte gearboxes? even if that is what is called for?

 

Depends on which page of the FSM you happen to read. It says use GL4 in the transmission in some areas, and that GL5 is fine in others.

Many folks have experienced troubles using GL5 in the gearbox, and been able to fix the shifting problems by going to a GL4 lube. That's why I mentioned the caution about using GL5 in the transmission.

 

all the lubes i have found all say exceeds gl-5 spec
and also they all say they are compliant with sae as well
on page A-34 under Service Specifications- Lubricants it says M/T Oil: API GL-4 or GL-5 SAE 75W-90

Under Differential Oil it says API GL-5 hypoid gear oil SAE 90 (above -18 degrees C)

Steering Gear box says API GL-4, SAE 90



Basically, what I am asking, is what should I use then?

 

also how much am i looking at in shop labor hours to have my TO bearing replaced with my own new bearing? I am really just too lazy to do it, but if it costs too much i will do it....

 

I've just changed my oil in t-case, tranny, front and rear diffs in my '99 taco, and used 75w-90 Royal Purple, ( I got it from napa about $9 a quart) and have had good results, it shifts alot better when cold, and better all around, i had been using non synthetic valvoline before.

 

i have been reading up, and in another thread, people have used GM Synchromesh in their trannies with reported awesome reults, this is what i now plan on using.... however, still a bit unclear on what weight and spec of fluid to use for the rear diff and the steering box.....according to my FSM, i am supposed to use GL-5 spec SAE 90 ... should i just go ahead and use 75w-90 instead? also what about the GL-4 spec SAE 90 i am supposed to use in my steering box? is the SAE 90 equivalent to both GL4 and GL-5? or would SAE 75w-90 suffice in this situation? I also plan on using a bottle of lucas oil stabilizer in each gear box (tranny,diff,steering)

 

anyone know?