I have a 4 speed manual transmission in my 86 Fiero. I am not exactly sure what the correct fluid is supposed to be. One lube shop said that it used a special GL4 or GL5 fluid. Another shop said it used GM part no. 1052931. The Fiero service manual has two listings. One is under manual transaxel; SAE 5W-30 (GM Part No. 1052931) Engine oil SF, SF/CC or SF/CD. The other is under manual transmission (rear wheel drive) 3 and 4 speed; Pontiac Firebird 4 speed manual 5W-30 SF, all others SAE-80W gear lubricant (GM part no. 1052271). It looks like the second listing applies only to Firebirds, but it doesn't say that. I would like to use pure synthetic lube in the transaxel. If this is simply SAE 5W-30 weight engine oil, then it won't be a problem. However, if it is some special gear lube, pure synthetic may not be available. Anyone have a book that clearly spells it out?

Ive had the same problem with my Isuzu 5 spd. I went to the GM dealer and they werent sure either. They said either 5W30 regular motor oil or Dextron Auto trans fluid. That sounds like 2 totally different types of lubes to me. Ive just been using the 5W30 oil since thats what the fluid looked like.

I would call Red Line Oil. I know they make transaxel fluid and it is all synthetic. I wish I knew more about this oil because I've heard some very good things about it and I would like to put it in my own car. Has anyone tried this product? Is it worth the higher price?

PaUL,
You are correct. Dextron 3 (aka. Ford Mercon) is for automatic transmissions. Gear lube is for manual transmissions. However, I believe the 4 speed and 5 speed manual transaxels for the Fiero use different fluid. For most manual transmissions an 80 or 90 weight gear oil is common. I had to order some window seals from a local Pontiac dealer. When I pick them up next week, I'm going to ask the dealer. If I have to, I'll go through evey mechanic in the shop till I find someone who knows what their talking about.

I have never seen a manual transmission use regular motor oil, they usaully use a gear oil like 80W or 90W. BUT the chilton manual says that all of the manual transmissions in the Fiero's use regular 5W-30 engine oil. If you are hard on your transmission though i would say put a heavier oil in it.

DO NOT put 80+ weight gear oil in a Fiero! Stock Fiero gear boxes use motor oil according to what I can find. This is NOT unusual in these transmisions. Some car makers even use ATF in the FWD manual gear boxes.

If you are racing, or taking allot of really long trips, you could go to a heavier oil like single 30, 10w-40 or maybe even 20w-50, but NEVER gear oil. If you do use a heavier oil, you could have problems shifting in cold weather.

"gear" oil is formulated much diferant from engine oil, and it is designed for an entirly diferant type of "cut" on the gears. Gear oil is typically loaded with allot of sulfer. Motor oil is nearly sulfer free by comparison. the 2 can never be used interchangably. neither can be interchanged with ATF.

Theogre is right. The original trans oil for this trans is SAE 5W30. Don't use hypoid gear oil. You won't like the results.
You can use a synthetic motor oil that replaces standard SAE 5w-30.
Write to Ed Parks at the Fiero Factory at Fierofactory@juno.com for details.
Hope this helps,
Carroll

Thanks for all the input. It was begining to look like SAE 5W-30 was the correct fluid, but the book never clearly spelled it out. I know some other manual transmissions that use engine oil as well. Although, gear lube is probably more common. My engine is still at the machine shop, probably will be for another week. It's going to have to bored out .030, and who knows what else at this point. It ought to run good when I get it back. I can't believe the egnine ran as good as it did while caked full of carbon. This is the only reason I wnated to have this engine rebuilt instead of getting another core. Can't wait to get it back, I'll keep you posted.

While your engine is at the machine shop throw in a 3.1 crank and 3.1 pistons, change the flywheel/flex plate and you will have a drop in 3.2 with no hassle

Phil,
That's a tempting thought. With the engine bored .030, it will bring the CID to around 177. A 3.2 CID is around 198. I don't know what the HP and torque figures are for a 3.2 mod, but I'm going to put a different cam in my 2.8. This should bring the HP to around 155-160 and torque figures to around 185-190ft/lbs. This should add a little kick to it. A stock Fiero easily does 0-60 (aka. 0 to a ticket) in less than 10 seconds. Most cars will these days. Unless your going to race at the drag strip, this is plenty fast for street use. I've spent some time in Germany, and I know what it's like to cruise the autobahn in a Beamer at 130 mph for 2 to 3 hours at a time. It's a whole different ball game than running your car to 130 mph for 10 seconds. Additionally, you don't realize how bad the roads are in the US until you've been on the autobahn. I would love to put a Northstar V-8 in my Fiero, but there is nowhere to drive the vehicle at the speeds it's capable of except the drag strip or Montana. Don't get me wrong, I love cars and I love speed, but it frustrates me to no end if I can't use it. However, I will say that if you ever get the chance to go to Germany, rent a Beamer and RAG IT OUT!

When i had to add some oil to my tranny, i just read the haynes manual and it said to use 5w-30, and that what appeared to be in the tranny at the time, so i use it. that was back in october, and i ve had no problems except for maybe the first shift into second on a cold morning its just a little stiff, but then it was always like that.

Carrolles,
I E-Mailed Ed Parks at Fiero Factory. He confirmed that the transaxel fluid for the Fiero is SAE 5W-30 engine oil. This is cool, because synthetic engine oil is easy to get, and is exactly what I wanted to use anyway. Thanks again for everyone's input.

ezsurf, as everybody said, don't put gear oil. When i first bought my 85GT, i brought my car to shop to change clutch when it done, they put gear oil and i had problem of shifting gear in the morning. I use 5W-30 Engine oil with gear up and it's working well!!

Oh man... I just had my Transmission checked and it was low on fluid. I asked them what they used, so I can do it myself next time, and he said they used Castrol Hypo C Gear Oil. SAE 80W-90. I don't have any trouble with it although it grinds a little going into 3rd gear. It sound like this was not the right stuff. What will need to be done before I can change it and is it doing damage?
Is the manual transaxel and the transmission two different things?

All you gotta do to change the fluid is drive it for awhile to warm up the fluid. In your case i would drive it a pretty good bit to warm up that thick fluid. Then at the bottom of the transaxle there is a plug. Just unscrew it and out it comes. Then to fill it locate the speedo shaft on the top of the transaxle and take out the bolt holding down the speed sensor. It's easy to find just find the wires that go into the plug in the sensor. Then just pour in the 5W 30(i recommend Mobile 1). There is a mark on the sensor that tells you how much to put in. I think it holds 4 quarts. Do you have the 4 speed? If you don't then the process may be different. The transaxle is the transmission. It's call transaxle beacause it's kinda part of the axle in a way.

I just used Dextron 2 for my Automatic. I had no problems whatsoever finding out what fluid I had to use because it was written on the dipstick (is that how it is called in English?)... Don't all Fiero's have that written on there?

If they only added enough "hyploid" oil, AKA "Gear" "Hyplo" or other 80+ weight gear oil, to fill a low transaxle, then they didn't do major damage. A small amount of this oil will generally only make shifting stiff.

You should drain the mixed oil as soon as posible. Replace it with new 5w30 in the distilled or synthetic of you choice.

As I mentioned above, "gear" oil tends to have allot of sulfer, and other aditives, designed to work with "helical" cut gears used in normal rear wheel drive systems. Fiero transaxles Do Not use this oil.

There is no dip stick on the standard transmission. You check the level by removing the speedometer sending unit. It has a level mark on it.
take care,
Carroll

Carroll, I think Cliff was just kidding us.

Cliff, you were just kidding us, weren't you?

Cliff...

Thank you for all the replies, I will change it this weekend.
Thanks again.

Actually Cliff is correct. I didn't know this but some 87 and all 88 manual transaxles do have dipstick. According to my Haynes manual.

i know i am a little late on this on but i think that you alll should know this.
1. there is a dip stick on most of the Isuzu 5 speeds
2. i put 10w30 sythetic oil in my transaxle and it made all kinds of noises, kinda like the cv joint going out. it wasn't because i just replaced the whole axle assembly with a new one. 3000 miles later i chnged that oil along with my engine oil and put regular 5w30 back in and have had no such problem since(till the damn trans blew up on me)

so thats all i know and have to say on this for now