final stages of starting up my car after a transmission and engine rebuild,,,,My question is how much of the following is needed
1. transmission fluid
2. differential fluid

Also what type of differential fluid do i need to use...Its a 73 olds 98 with all stock equipment...

 

For the transmission fluid, the TH350, TH375, and TH400 all take 10 quarts after a complete overhaul.

For the differential fluid, it depends on the size of the ring gear, and I don't know which one is in the 98. For 8.5" ring gear with 10 bolt cover its 4.25 pints. For 8.875" with 10 bolt cover or 9.375" with 12 bolt cover, it's 5.5 pints. I'm guessing that if you have a 12 bolt cover, you'll know exactly which one you have. If you don't know which one you have and it's a 10 bolt cover, put in 4.25 pints. If that doesn't bring it up to within 3/8" of the filler hole, add another 1.25 pints as you must have the larger of the two ring gears that use a 10 bolt cover.

As far as the type of fluid to use in the differential, the manual says the following: "Maintain lubricant level within 3/8" of filler plug hole with No. 1051022, 1050081, or SAE 90 G.L.-5 or equivalent." When I replaced the differential fluid on my '64 Jetstar 88, I bought 90-weight gear oil (SAE 90) at the local auto parts store and had no trouble.

The above is for conventional differentials. If you have the "anti-spin" differential, it just says to "maintain lubricant level within 3/8" of filler plug hole with No. 1051022 or equivalent." It seems that you can use 1051022 in either transmission but the other two mentioned in only the conventional.

What does "or equivalent" mean? If all three are fine for the conventional, they must be "equivalent." So why aren't the 1050081 or SAE 90 good to use in the anti-spin? The book doesn't say. What I've quoted above is what the 1973 service manual says.

 

Not compatible with the clutch material in the Anti-Spin unit.

Norm

 

i went to the part store AND walmart and can only find 80w-90 gl5,,,would this work..

 

That's what I used in my '64 Jetstar, and that's what the manual says is an acceptable alternative as long as you have a conventional differential. Do you? Or do you have the anti-spin? If the latter, I would think you would need to find fluid specifically for that, and I don't think Walmart would be the place to look.

If a run of the local auto parts stores doesn't turn up what you need, you could try the parts counter at a local GM dealer. They might not have the fluid, but they might know where to get it or can order it.

But first things first. Do you have a conventional differential or an anti-spin differential? It would seem that you can't proceed until that question is answered.

 

from looking athe manual,,,,i think mine is the convential differential,,,is there away to tell for sure though...

 

First of all, which manual are you referring to? If you have the service manual, then you already had all the information you asked for earlier with regard to capacities and what types of transmission and differential fluids to use. The '73 Olds Chassis Service Manual describes transmission identification on page 0-4 in the "General Information" section and on page 4B-33 in the "Differential" section.

If you don't have the manual, to determine which transmission you have, you'll have to find the differential ratio code which is stamped on the right front inboard side of the axle housing tube. There will be three letters and three numbers. The three numbers indicate build date, and the book doesn't say how to decode them. But the three letters are what you need.

The first two letters indicate both the gear ratio and whether or not it is anti-spin. For the 98, there are six possibilities for those first two letters. NA, NB, or NC would indicate a conventional differential with gear ratios of 2.73, 2.93, or 3.23, respectively. RA, RB, or RC would indicate an anti-spin differential with the same gear ratios. So what you're looking for is the first letter of that three-letter code stamped on the axle housing. N = conventional differential, R = anti-spin.

The third letter, by the way, indicates the manufacturer of the transmission. All 98's should have a letter "O" as the third letter as all were made by the same manufacturer. It doesn't say who the manufacturer was.

 

i cant seem to find the stamp of what type of differential i have,,,i have sanded all the grime and what not off to see if i can find it and have had no luck,,,i do have a 12 bolt cover that i know,,,

 

All I can suggest is, are you sure you're looking in the right spot? These number and letters are punched in. It would take a fair amount of corrosion for them to be worn off, and if there were that much corrosion or wear, I would think you wouldn't have any axle housing left. Otherwise, maybe someone else will know a way to tell the differentials apart.

The 12-bolt cover indicates the 9 3/8" inch ring gear which would mean it takes 5.5 pints of differential fluid. But that's the only ring gear size that was available on the 98, so it won't help in determining the differential type.

 

could u give me a more specific spot,,,so its stamped on the passenger side axle tube correct,,,,is it facing the front or rear of the car?,,Rearend isnt corroded but there was alot of oil from where the pinion seal was leaking for who knows how many years...thanks for your help

 

"right front inboard side of the axle housing tube" is word for word out of the service manual. From what I can tell in the pictures, it should be on the passenger side, facing forward, between the differential and where the coil spring and shock absorber attach to the axle. I think that's what they mean by "inboard." "Outboard" would be between the spring/shock attaching points and the wheel. The letters/numbers are 1/4" high.

 

OK,,,,i just got done from underneath the car and looked everywhere where the manaul said it should be,,there is nothing there,,,However i did find raised number and letters on the front bottom of the differential housing...on the passenger side front of the housing there were the numbers 406208,,on the drivers side front of the housing there was a flat head screw looking design and then a circle with lines through it,,and then the letters CFD,,,,Up top on the drivers side of the diff. housing there were a B and N,,,,There is no stamps of numbers or anything on the axle tubes like the manual shows..

 

UPDATE

I found the code,,,,,It starts out with a NA,,,,per manaul it is a conventional diff.,,,,,
Thanks Jaunty75,,,4:55 am i found it,,,lol,,,,,

 

Cool! I know it was late, but I bet you slept better. You should be able to put that 80W-90 oil in just fine.

 

Hello I have a 1976 Oldsmobile cutlass supreme 5.7 Liter Does anyone know what type of transmission fluid I need and capacity? Thanks in advance

 

Just go to the nearest auto parts store and buy your favorite brand (Castrol, Valvoline, STP, AC/Delco) of "Dex/Merc" or "Dexron VI." Read the labels as they'll say right on them that they're compatible "with all GM vehicles" or "with all GM Hydramatic transmissions." It's pretty hard to do this wrong.











As far as how much you need, that should be in your owner's manual and certainly it's in your factory service manual. According to the factory service manual, for the TH350, 375, and 400, it's 3 quarts if you do just a drain and refill, 10 quarts after a complete overhaul.

 

Thank you unfortunately I dont have a manual, My trans cooler line broke so all my fluid came out when Driving the car. Luckily I pulled over fast and got towed home.My car is a 5.7 litre V8 350 engine. Really appreciate it