Gear oil question

[YJBLUE]

Hey all:
I need to change the oil in my 5 speed transmission and I was hoping someone could guide me in the right direction. I have the Peugeot BA 10/5 transmission and I'm hearing all kinds of things about what to use. Some say regular motor oil and some say 75W 90 gear oil (GL3 only). :???:
Does anyone have a suggestion based on their own experience or technical knowledge? I would appreciate any help I can get on this. I'd hate to ruin a trans thats running okay at the moment. Thanks in advance.

Mike
1988 YJ with 4.2L engine

 

[TwistedCU]

Hey all:
I need to change the oil in my 5 speed transmission and I was hoping someone could guide me in the right direction. I have the BA 10/5 transmission and I'm hearing all kinds of things about what to use. Some say regular motor oil and some say 75W 90 gear oil (GL3 only). :???:
Does anyone have a suggestion based on their own experience or technical knowledge? I would appreciate any help I can get on this. I'd hate to ruin a trans thats running okay at the moment. Thanks in advance.

Mike
1988 YJ with 4.2L engine

The 75W90 GL3 is for the AX5 and AX15 trannies that came after the BA 10/5's.

Everything I have read says stick with 10W40. A semi-synthetic is OK but full synthetic is supposed to cause issues with the synchros. I cannot personally verify that.

FWIW the 88 YJ I had for about a year had regular old 10W40 in it and shifted smooth as silk.

The recommended oil is non synthetic 10w40. That's what I would use.

 

[YJBLUE]

Thanks for the reply. I'm just wondering why one manual trans (AX15) needs 75w-90 gear oil while another trans(Peugeot BA 10/5) can get by on 10w 40 motor oil? Aren't they somewhat similar inside? Just curious.....
Also, you mentioned that you had an 88 YJ (with the BA 10/5) for about a year. What did you think of the trans? I hear a lot of bad things about it but so far mine seems fine.

Mike

 

[TwistedCU]

Thanks for the reply. I'm just wondering why one manual trans (AX15) needs 75w-90 gear oil while another trans(Peugeot BA 10/5) can get by on 10w 40 motor oil? Aren't they somewhat similar inside? Just curious.....
Also, you mentioned that you had an 88 YJ (with the BA 10/5) for about a year. What did you think of the trans? I hear a lot of bad things about it but so far mine seems fine.

Mike

The AX series is japanese made, the BA 10/5 is french. Totally different trannies, but made for similar applications.

The BA 10/5 I had in my completely stock 88 YJ shifted smoother and was geared better (for daily driving mind you) than the Aisan Warner transmission in my '92 YJ. I worked flawlessly. The problem with them is when you get bigger tires and add heavy accessories and go 4 wheeling. They are notoriously weak and prone to failure.

For a stocker they aren't bad at all.

 

[Bounty__Hunter]

I had an '88 YJ with the Peugeot BA10/5 transmission and never had any problems, even after putting a built 350 in front of it and wheelin on 33" tires. I think some of the hype about it is BS.

 

[YJBLUE]

Thanks Bounty Hunter. Did you also run it with 10w40 oil in the Peugeot trans? Would it do any harm if I used 75w 90 GL3? I heard that Peugeot recommends 10W 40 motor oil but a Jeep dealer I called claims straight 90w is needed. I'm going crazy.........

 

[Bounty__Hunter]

I don't recall ever chaning the fluid in that jeep, but 90w sounds kinda heavy. I'd check around a little more, maybe at a few parts stores.

 

[Megamole]

YJ Blue I am in the same boat as you or transmission if you will. Parts store told me 75w-90, my manual for the jeep says SAE75W-90 (API-GL5) grade. My biggest problem is I can't get the fill plug out. What kind of tool are you using? I can"t find anything to fit.

 

[TwistedCU]

YJ Blue I am in the same boat as you or transmission if you will. Parts store told me 75w-90, my manual for the jeep says SAE75W-90 (API-GL5) grade. My biggest problem is I can't get the fill plug out. What kind of tool are you using? I can"t find anything to fit.

what year is yours... if it is a 90-newer don't put GL5 in it... it'll kill your synchros (the manual was misprinted).

Call a dealership to verify this if you must.

 

[YJBLUE]

Hey Megamole: The square hole in the fill plug is 5/16. I've heard others say that 8mm will also work. I went to my local hardware store a bought a 1 or 1.5 inch long piece of 5/16 square metal stock. Once its inserted in the hole, I use a 1/4 inch wrench to turn it. It works fine.
As far as the oil goes, I tend to go along with Twisted Copper and 10W40 motor oil. I saw a thread that says this is what's recommended by the Peugeot owner's manual (for a Peugeot car with a BA 10/5 transmission). On the other hand, a nearby Jeep dealer claims he looked up the spec and it calls for straight 90w oil. One thing I do know: you should not use a GL5 oil. It contains sulphur which will eat away the synchros. If you use a 75w 90 oil, make sure its GL3, which has no sulphur. I'm looking at this oil because I've seen threads in which others swear by it. It's also the oil recommended by Jeep for the AX5 and AX15 transmissions (manual was a misprint).
It seems the more threads I read, the more negative and positive things appear about both (10w 40 and 75w90w GL3). Crazy........:???:

Mike (YJBLUE)

 

[Megamole]

YJBlue
Thanks I really appreciate the info, hopefully I can get it off tomorrow and give the gears a well deserved lube.8)