What is the best thing to use in a Manual Festiva Transaxle?

[Greywolf]

The book calls for Mercon Transmission fluid, but William (FF.COM member) told me that they came from the factory with motorcycle oil in the gearbox...

I'd appreciate all the feedback on this I can get - especially from long time Festiva owners, and particularly from folks that have raced them like AdvancedDynamix.

Whatever does the job the BEST is what I want in mine, and I have heard that running gear oil in some kinds of Toyo Kogyo trannies will just plain kill them.

I now open the floor for extensive discussion - no flaming please, I'm sure at the worst we can agree to disagree

~Wolfie

[FestYboy]

Wtf is what should be in there, but there have been several instances where an untouched trans was drain just because of milage, and 30 weight oil came out.
Both Mazda and Ford call for atf.

[Team Lightning]

I use Pennzoil Synchromesh in mine. It Shifts easier too.

[william]

I said my untouched trans had gear lube or something similar.
And the motor cycle oil works well.
I've ran atf, 70-90, and 20-50 bike oil and I like the bike oil .
But I've had 2 different trans last over 300k one with gear lube one with atf. Gear lube kinda sucks when it really cold other then that it works well.

[bhearts]

I use Pennzoil Synchromesh in mine. It Shifts easier too.

Pure sincromesh?

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[Greywolf]

What weight of synchromesh? That sounds like a synthetic, but I'm open to all ideas. I'm also interested in LONG TERM results from people who have been running "ALTERNATIVES TO OEM" for a considerable length of time - enough to prove or disprove longevity in the real world.

The bottom line is a search for what makes these trannies last the longest and work the best. If we can pin that down - it's a giant step forward.

[TominMO]

So many people use so many different fluids, I am beginning to think you could put darn near anything in there. I use 20W50 racing motorcycle oil, because Charlie does. Works great and doesn't leak from the seals.

[Team Lightning]

Synchromesh straight out of the bottle. That's what I use in my 90.

[WmWatt]

Incremental performance enhancements pobably depend on the kind of driving you do and where.

[fezzy]

There are volumes on the science regarding gear oils.
I know this, that a morris mini minor used engine oil for all 3, that is engine/gearbox and diff.
A quick google and found some basic answers such as ;

20-50 oil was developed by austin-morris (BLMC) especially for the new mini released in 1959.

this oil was different to the previously used oils , because it had to lubricate the gearbox and diff , on the new transverse engine.

The above answer in principle illustrates the engineers have to have specific oils developed for unique situations., so their recommendation was the 20-50.

The Festiva 5 spd manual and auto in some cases use the same oil, and it happens to be Dextron Auto Trans oil, yet on the other side of the hemisphere, a similar model vehicle uses Gear oil for the manual and Auto Trans oil for an Auto.
So the question here is, what is the fundamental difference inside the manual gearbox between Australian conditions and Canadian or USA ? Because I have both workshop manuals and both write 2 different oil types when it comes to the oils for these transmissions.

As a lay person with non engineering experience at metallurgy level for gears etc, I have no way of forming an opinion, but do understand it is critical when brass ( synchro rings ) meets metal during a gear shift, and the angle of the gear cuts as well is critical for correct oil type.

How then on earth did the engineers of the Morris Mini Minor overcome this when engine/gearbox and diff used the same oil at the same time, when brass synchro rings, engine heated oil, gearbox and diffs all worked in harmony?
Or was this car later on found to be high maintenance in the long run and the idea was shelved?

Personally, for now I will stick to what the book says that came with the car that is in the glove box, simply because I am not at this phase of the Festiva thing at liberated finances to temp and experiment with oils.
I do want to use thicker gearbox oil and not the Dexron, but then again are the oils seals capable of holding due to the material is only suited for Dexron and not gear oil.
Same question is, are the oil seal materials of different compound when applied to gear oil than one that uses Auto Trans oil, or are they similar compounds?

And finally, why did Ford/Mazda/Kia insist on Dexron for all 3 , Gearbox, Diff and Auto ?

[sketchman]

I just wanna point out the first response said to put WTF in it. LOL

[FestYboy]

That's right!!! Lol

[blake4591]

I'll offer some comments as a guy that does engineering on drive train components for OEMs.

I would put ATF in the trans first and then maybe the motorcycle oil. I wouldn't use anything over a 20w50 because it'll either make it shift really hard in the winter or run to hot in the summer.

ATF is actually a pretty interesting fuild because it has to work with clutches and gears and be thin enough to be easily pumped. Clutches need friction modifiers to help them stop slipping and lock. Basically as an auto trans shifts the clutches start with a high delta speed and reduce it until its zero. To help them do this friction modifiers in the oil increase the shear strength of the oil to be able to support the torque transfer to get the delta speed to zero. Without the friction modifiers the apply pressures would need to be much higher and the clutches much bigger (think manual transmission clutch). The planetary gears in the transmission need a fluid that has a high film strength to prevent metal to metal contact. Both of these make the fluid more difficult to pump so there is a very delicate balancing act. This is why when GM first released their Dexron 2 oil spec in the 70s the name became the standard for ATF. It was the first really controlled ATF fluid that was used by an OEM, Ford had type A and then type F I think and now they use Mercon, GM still uses Dexron 6 and Chrysler uses ATF+4. These are fluid blends that are unique to each OEM to this day.

This all effects manual transmissions because in the 80s as manuals were being phased out the OEMs didn't want to stock and track different types of oil. The autos had to use ATF so they started putting it in the manuals as well. It is designed to work with gears so it's not going to hurt the manual trans. Some transmissions may have had some small updates to the gear geometries but most were just switched over. After ATF was pretty much standardized in manuals things like fiber line syncros started popping up that only really work with ATF. Manual transmissions after about 1985 were basically designed and developed knowing that they would be filled with ATF and I don't know of any car transmissions from that time to now that don't spec ATF as the fuild. Some truck manuals (mostly NV stuff) were still using a gear oil but that was due to higher loads of the truck applications requiring higher film strength.

Gear oils 70w90s etc. are really for ring and pinions. The contact stress is extremely high in a ring and pinion system and you need a lot of film thickness which results in very high shearing heat. Using gear oil in a transmission without the correct clearances for the oil will result in a transmission that runs very hot and has high parasitic loses. The old manual transmissions that used gear oil have different tolerances to allow the thicker oil to work.

edit: I forgot to talk about oil distribution. most manual transmissions relay on oil splash (as in the have no pump) to make sure everything that needs oil gets it. Oil splash is heavily effected by viscosity. Thicker oils may not be able to get into critical areas like the thinner oils can. For anyone that has had the inspection cover of a G series transmission there is a catch pocket and feed tube to feed oil into the mainshaft of that trans to lubricate the gear bores. It's pretty easy to tell that ATF will flow through that feed tube faster than a 85w90.

[Greywolf]

Anyone have an opinion on whether synthetics will last longer than dinosaur juice?

[TorqueEffect]

Pennzoil synchromesh is what I run. no issues. I did have a shift gate break on my original 5 speed, but that isn't the oils fault.

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