Best transmission oil?

GTSSportCoupe · Post by **GTSSportCoupe** » Thu Mar 17, 2005 12:10 pm

Ok, I know this has been brought up in other posts before, but I thought I would bring it up again to see if anyones opinion has changed.

Price aside, what is the best possible gear oil I could put into my high km manual transmission?

I put some cheap 75w90 gear oil into my manual gearbox and rear diff when I bought my 86 terc 4wd (about 8 months ago) with the intention of letting it 'rinse' the insides before I put good oil in (because the old oil that came out was NASTY).

In my previous 87 terc 4wd I had put in Redline synthetic gear oil. The only problem I have with the synthetic oils is they seem to create leaks where there were none before.

Currently whenever I start driving before the gearbox oil warms up, the 2nd gear synchro tends to protest a bit (a little rasp), and all gears are a little hard to engage. Once warmed up it works good, although I always seem to have lots of gear noise from the trans/fron diff as well as the rear diff.

What do you guys think? What type of oil do you have in your gearbox?

Thanks,

Nick

Retroloc1 · Post by **Retroloc1** » Fri Mar 18, 2005 1:20 am

Your speeds are hard to engage. Are you sure you clutch cable is correcly tuned ? (completely disengaged with the pedal to the floor)

takza · Post by **takza** » Fri Mar 18, 2005 6:07 am

I went with 40% 75W90 synth and 40% 85W140 regular gear oil with 20% Hyperlube Racing Formula additive.

Hyperlube Racing Formula additive...almost as heavy as the old STP was...it will "string" if put between your fingers...while oil just "globs". What good is it? Supposed to help the oil cling to the gears...jojobo oil supposed to be a super lube.

Similar to the Lucas additive???? Some claim that Lucas causes oil foaming though.

This is heavier than just an = 90 and 140 W mix.

Result? have less leakage at the 4WD shifter shaft...some minor gear clashing when cold...goes away warm....seemed to quiet it down a minor amount.

If I remember well enough...I also had some gear clash cold with all 90W.

IMO, with these high mileage trans...heavier oil can't be too wrong.

Basically.....I'd choose 3-4 quarts of cheap gear oil over 1-2 quarts of synthetic any day....

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GTSSportCoupe · Post by **GTSSportCoupe** » Fri Mar 18, 2005 8:56 am

Thanks very much takza! I was thinking of doing something similar to you (mixing additives with a couple types of basic mineral oil). I'm wondering if there is anything I can do to get rid of the stiffness of the trans when it is cold though....? I guess that would mean a less viscous oil rather than more?

takza · Post by **takza** » Fri Mar 18, 2005 9:07 am

I can remember a '76 Corolla that you almost couldn't get to shift below 0 F when cold...my wagon needs some double clutching to get into 1st when serious cold hits...clash goes away in 2-3 miles or so.

I think it was about the same with all 90W...probably a little less.

I can live with this minor clash if the trans lasts a while longer.....not too many trannys last over 220K miles?

IMO...light synth gear oils are meant for racing and where you just have to have the least power loss at some expense as far as longevity.

3A-C Power · Post by **3A-C Power** » Fri Mar 18, 2005 10:46 am

You remeber my experience with the Redline oil - great improvement in synchro engagment at first, but toasted the trans within a year.

In my new trans I used cheapo 80W90 like you did with the intention of cleaning the crap out. I had the trans apart and inevitably there was a little crud that I couldn't clean as it was only partially apart. Well that cheap oil has been in there too long and it doesn't work that well. All around poor synchro performance especially in the cold. I plan to try out another synthetic.

In my experience the Z tranny makes noise when it gets older and the oil does nothing to fix it. I believe most of the noise is due to the the front input shaft bearing. This bearing can be replaced without taking the whole tranny apart (not the way it is in the FSM, but it can be done). This bearing is a cylindrical roller that comes as a press-in outer race and roller cage, and it uses the ground surface on the input shaft itself as the inner race. If the bearing is bad, chances are the surface of the input shaft is equally at fault as the rest of the bearing. If you found the right shop, you could get the shaft hard-surfaced and reground. Now if you had the trans out anyways, the thing to do would be to overhaul it meaning new bearings and replacing at least 2nd and 3rd synchros with the new and improved ones that Toyota made. Before that time maybe try a good manual transmission specific synthetic oil but keep an eye on it so you know if it's breaking down like my Redline did.

GTSSportCoupe · Post by **GTSSportCoupe** » Fri Mar 18, 2005 1:32 pm

Thanks 3AC, I really appreciate the info. Maybe I will try another high quality synthetic oil and keep an eye on it. I'm going to hold off as long as possible on a rebuild of the trans (bearings/synchros).

GTSSportCoupe · Post by **GTSSportCoupe** » Fri Mar 18, 2005 3:34 pm

Well, I was at NAPA and decided to see what their best oil was. They had a Castrol full synthetic that the guy gave me for a great price...can't beat a good oil for a good price, so I went for it. It says it maintains excellent stability over a large temperature range...we'll see how it works out. I also bought an addititve (don't remember the name) that I'll add if I'm not please with the performance.

Thanks for your help and ideas takza and 3a. I'll report back when I get everything changed out. I'm going to put some of this stuff in the rear diff too.

Typrus · Post by **Typrus** » Sat Mar 19, 2005 12:02 am

I'd say try Amsoil, but you already bought something. Great oil for its price. We have friends with Ford Powerstrokes with the Auto tranny running 80 horses or more over stock, running with Amsoil in the tranny for anywhere from 60k-120k miles on them, no big issues. The manuals, no reported issues.
The reasons synthetics "create" leaks is that they clean deposits out. Deposits may form over a deteriorated gasket or seal, creating a "fix" that turns into a big issue. The synth cleans it out, just showing a problem that already existed.

GTSSportCoupe · Post by **GTSSportCoupe** » Mon Mar 21, 2005 8:39 am

Well, I put the new oil in this weekend....and it completely TRANSFORMED my transmission!! Its absolutely unreal. Shifts like a brand new trans now, even when cold. Lots quieter too, it just has that normal whine that all tercel transmissions have. The shifter slides into place so easy now and never have and rasp/grind when putting into gear cold. For now I highly recommend the oil; we'll see how well it stands up.

GTSSportCoupe · Post by **GTSSportCoupe** » Tue Mar 29, 2005 6:20 pm

I said I had put Quaker State in before, I was actually confused, I looked back at the bottles the other day and saw it was actually Castrol oil. Good shit tho!

Typrus · Post by **Typrus** » Wed Mar 30, 2005 12:30 am

Castrol and Mobil are the big mainstream synth companies. But again, Amsoil beat them out in all tests. Its incredible shit. lol.

3A-C Power · Post by **3A-C Power** » Wed Mar 30, 2005 8:40 am

That's great that it worked so well. What is the oil called exactly? I'm inclined to use the same stuff in my trans now that there's a good review from a real Tercel owner.

GTSSportCoupe · Post by **GTSSportCoupe** » Wed Mar 30, 2005 8:48 am

3A-C Power wrote: That's great that it worked so well. What is the oil called exactly? I'm inclined to use the same stuff in my trans now that there's a good review from a real Tercel owner.

I'll take a look at the bottle when I get home so I can tell you exactley what the stuff is called. I got it at NAPA.

Typrus · Post by **Typrus** » Wed Mar 30, 2005 10:39 am

Amsoil. Go to their website. They have application guides.
Someone who was posting here for a while was an Amsoil distributor... Who was it....
Well at any rate. Maybe I could convince you to blend half-half. Lol. They are compatible.
Amsoil is rated for 100,000 miles in trannies and differetials.
25,000 miles in an engine. Of course the Super Duty bypass filter they offer must be changed at 12,500 mile intervals.