atf or gear oil

[william]

So when i bought my festy in June of last year, my cv shafts were shot so i replaced both sides (cheep remans) lol when i pulled the cv's i knew i would lose some fluid so i picked it up when i got the shafts i got gear oil not sure on the weight ,but it was royal purple (good stuff) i have always used it with good luck .. but then i got my 2nd festy and pulled the motor it had atf not gear oil so i did some looking and thats what it calls for i have never herd of this before with a mtx would the gear oil i used on my 1st festiva hurt the trans?

[batstiva]

Yep, the manual calls for ATF. Having said that, when I swapped Batstiva's shafts, I ended up using gear oil (because somebody forgot that pulling the shafts would result in a loss of fluid :banghead
Anyway, the gear oil I used worked just fine. Put about 25K miles on the car afterwards, before having to park it for reasons not related to the tranny. I think you'll be fine with the gear oil.

[william]

Thinks, that whats i wanted to hear i plan to do a bp swap and trans but it might take some time so i just wonted to know that the stock one would last.

[blkfordsedan]

IIRC, the Kia Pride or Mazda 121 manual actually calls for gear lube (?)
Maybe someone can confirm that. I have considered trying GM Syncromesh when I finally get around to swapping my B6. ATF is pretty common in MTX nowadays, but I always worry about not having the EP (extreme pressure) additives that the old gear lube had. One note about synthetics, you need to make sure the seals and syncros (brass or whatever) are compatible, not usually a problem on more modern cars.
Case in point, the Tremec TR3650 in my Mustang is supposed to have some type of carbon fiber syncros. According to Tremec, using a synthetic like Royal Purple or GM Syncromesh will attack the adhesive used in the bonding process and result in syncro failure. However, 50% of the Mustangs w/TR3650's on the road are filled with one of these 2 fluids, and are not having any issues. The other 50% either still have the factory Ford fill (which was Mobil1 Synthetic- go figure), or Mercon ATF like the manual calls for.
In any case, RP should not cause any issues in the Festy. Worst case, If the seals are original OEM they may start to leak, but chances are you replaced them with modern seals anyway. Also, there is such a thing as being "too slick" when it comes to syncros. If you experience gear crunch when shifting, that may be the problem. If it shifts good & doesn't leak, you're good!

[1988festivazoom]

im just gunna say that royal purple is a joke. its 10$ a quart and inferior to amsoil, and amsoil cost less, and has warranty aginst damage caused by lack of lubercation. ive run atf and gear oil, gar oil in summer and atf in the winter time.

[econoaddict]

im just gunna say that royal purple is a joke. its 10$ a quart and inferior to amsoil, and amsoil cost less, and has warranty aginst damage caused by lack of lubercation. ive run atf and gear oil, gar oil in summer and atf in the winter time.

Over the years I have seen people try to make a claim on that warranty from amsoil, always needed documents from us (the repair shop) and usually ended up not being covered for various reasons. The main one was that the failure had to be directly caused by oil failure, they want proof it was caused by the oil not a defective or worn out part. example: your oil pump fails, you have to prove the oil caused the pump to fail....good luck

I am not saying amsoil is bad stuff, it is actually a very good product from what I have seen.
I would use it over royal purple in a street car any day.
Royal Purple contains Moly that can potentially cause issues under extended use.
Basically boils down to different oils have their place/uses.

What oil or brand of oil is a subject that will be debated till the world ends :p

[1988festivazoom]

the nice thing about amsoil is i send them an oil sample every 3 months and they will send me results on the oil sample like visc. breakdown and if there are any metals that are cause for concearn ect. and they will tell me how much life the oil has left. they said as long as i do the samples as required, they will cover any failure... not sure how true it is but i used royal purple and wasant impressed by the product..... its stupid that it is dark colored to begin with bc how the hell are u supposed to know when it darkens up lol

[91_festy_Gl]

I use syncromesh in both mine and never had problems.

[blkfordsedan]

I use syncromesh in both mine and never had problems.

How do you like it? Does it seem to make a difference?

[angrygocart]

I was told by a Ford tech who has owned numerous Festivas that they came with gear oil. He used atf in the trans. You shouldn't have problems with either one. Gear lube is thicker and may not be ideal for cold climates.

[blkfordsedan]

I was told by a Ford tech who has owned numerous Festivas that they came with gear oil. He used atf in the trans. You shouldn't have problems with either one. Gear lube is thicker and may not be ideal for cold climates.

I can believe that. My '93 had like 34K original miles when I got it. I changed the trans fluid at about 60K and it looked like regular gear oil. I seriously doubt it had been changed before I got it.

[timmay89]

I put in gear oil almost a half a year ago. Through out the winter though it the tranny has been more difficult to shift than I expected it would be. I am not sure if it is related to the oil, but I am not happy with it as of yet.

[drddan]

Had the 5 sp manual tranny in my F-150 rebuilt, and the guy that owns the shop insisted I fill it with transmission fluid. I asked about the gear lube, and he said that they run better and cooler with the tranny fluid. I filled it with tranny fluid and have not had any problems. This guy, and his father, who used to own the shop, are top line rear end and tranny rebuilders and have built ford 9 inch 3rd members and chevy 12 bolt's for me in the past. I trust what he says.

[FestYboy]

IF you use oil, use a light weight (10-40 or 20-50) but NOT gear oil. the manual specifies ATF for a reason, it needs to be and stay thin to properly lubricate the bearings and syncros.

[Fordverde]

but I was under the impresion that gear lube 80w90 is equal as 30w? I think I read ot some where