'58 BW T10 Lube Procedure

[David B.]

A few rookie questions about my Borg Warner T10 4-speed:

- Where is the fill plug? Can't seem to find a picture.

- How do you tell when the oil level is correct?

- Is NAPA Stalube GL4 the right oil?

- Other lube tips?

Bonus question: What oil for the differential? GL4? GL5?

As always, thanks, guys!

Dave

[John F.]

Re: '58 BW T10 Lube Procedure

David, there should be a plug on the passenger side of the main case. 90 weight gear oil is the same for the trans and the rear end. Remove the plugs from both and fill to where you can feel it with your finger. Just a little below the hole. Clean up the threads and snug back up. You don't need to overtighten.

[Don H.]

Re: '58 BW T10 Lube Procedure

Dave, The transmission filler is a square head plug on the right (passenger) side. I use 70-80 weight gear lube in both the tranny and rear end (with posi additive if it is a posi in the rear end). Both you should feel the fluid with your finger when you reach in but do not fill all the way to the hole. Good luck, Don H.

[John H.]

Re: '58 BW T10 Lube Procedure

A few rookie questions about my Borg Warner T10 4-speed:

- Where is the fill plug? Can't seem to find a picture.

Dave -

Your T-10 has two plugs - the upper one is the fill plug, and the bottom one is the drain plug.


60T10_1800.jpg

[Bruce B.]

Re: '58 BW T10 Lube Procedure

Dave,
Just so you don't get surprized; after you fill the trans there is a possibility some oil might leak out the countershaft hole (I think thats what its called) at the front of the transmission. You can't see the shaft with the trans in the car but you might see oil. It is no big deal and it will stop leaking when the oil level goes down below the shaft hole.
The shaft hole can be sealed with silicone if and when you have the transmission out of the car.

[David B.]

Re: '58 BW T10 Lube Procedure

Gentlemen, thank you all so much for the great wisdom. John H., that picture is exactly what I needed. All the pictures that I found showed the unit from the driver's side.

I take it that as long as I use 70-to-90-weight gear oil, I'll be okay. I found a lot of fuss on some other tranny forums about GL4 vs. GL5. Is the GL spec really that crucial?

By the way, I'm having a little trouble shifting into 1st and reverse. Is that a symptom of low oil or a synchronizer issue?

Dave

[Don H.]

Re: '58 BW T10 Lube Procedure

Dave, The shifting problem could also be the linkage adjustment - hopefully an easy fix. Don H.

[Cecil L.]

Re: '58 BW T10 Lube Procedure

On 57-58 should be filled to 1/2" below the filler hole. In 59, the case was changed to move the filler hole down to prevent overfilling. It then would be filled to the bottom of the hole.

[Duke W.]

Re: '58 BW T10 Lube Procedure

The original spec for the transmission and axle oil was Mil-L-2105. This mil-spec was cancelled some years ago and replaced with API 80W-90 GL-5.

There are stories on the internet about "synchornizer corrosion" from GL-5, but I have yet to see any documented evidence of synchronizer corrosion on these 50-year old transmissions, some of which might still have the original factory fill oil in them. It's amazing to me that guys believe all these stories without a shred of evidence.

I am aware that there is some evidence that GL-5 may cause "yellow metal" corrosion at very high temperatures - on the order of 250F or above, but it would be rare for the oil in the transmission to exceed 200F - maybe in serious road racing in hot weather. It appears that some oil marketers are hyping this issue to promote their products, but I think it's bunk!

GL-5 has an EP additive that is absolutely necessary for the hypoid gear set in the axle. GL-4 lacks this additive and GL-4 is the typical spec for modern manual transmissions and transaxles that don't contain hypoid gears. Modern Corvettes have a sort of "transaxle", but the axle and transmission parts of the unit are isolated. They each have their own oil supply - GL-5 in the axle and GL-4 in the transmission.

The trend toward "lighter" manual transmission oils started with new designs in the seventies. Many speced ATF, which has a SAE gear oil viscosity range of 70W-75 with a GL-4 rating. This proved inadequate in some cases, which started a trend to synthetic based 75W-90 GL-4s. Since the EP additive is only necessary for hypoid gears, it follows that GL-4 might be okay for vintage transmissions that specified Mil-L-2105, but I am aware of no long term durability tests that support this conclusion, so my recommendation is to stick with GL-5 as there may be detail internal design differences in modern transmissions that make them compatible with GL-4.

If you have a Positraction axle, you will also need the anti-chatter additive.

Duke

[Douglas C.]

Re: '58 BW T10 Lube Procedure

Good ole 80 - 90 fluid will be good, just don't use synthetic fluid.

Ask me how I know!!

[David B.]

Re: '58 BW T10 Lube Procedure

Don, where do I need to go to learn about linkage adjustment? Thanks.

Dave

[David B.]

Re: '58 BW T10 Lube Procedure

Cecil and Duke, thanks for the clarifications. I'm a rookie in training. :-)

Douglas, is the answer: "It leaks!"?

Dave

[Douglas C.]

Re: '58 BW T10 Lube Procedure

Cecil and Duke, thanks for the clarifications. I'm a rookie in training. :-)

Douglas, is the answer: "It leaks!"?

Dave

Hi Dave,

I'll assume Muncie and T-10 internals are very similar. I remember rebuilding my Muncie in my 69 SS 396 Chevelle about 10 years ago. I thought I would be extra nice to the car so I put Valvoline 80-90 Synthetic trans fluid in. Well, I got I think about a mile down the road, heard this clunking / groaning sound, limped back home. I called the 4-speed parts dealer, told him I was sure I did everything right; syncros, individual rollers packed with grease to hold in place is assembly, etc., even did syn. fluid.

Whoops he said, syn. fluid does not have the cushioning effect of old style thick fluids, old transmissions have sloppy clearences, so pull it out and open it up. If will look like a box of Corn Flakes inside. He was right. That's how I know.

Hope this helps.

Doug

[David B.]

Re: '58 BW T10 Lube Procedure

Forewarned is forearmed, Doug. Thanks for the heads-up. Sorry you made Corn Flakes.

Dave

[Dick W.]

Re: '58 BW T10 Lube Procedure

The original spec for the transmission and axle oil was Mil-L-2105. This mil-spec was cancelled some years ago and replaced with API 80W-90 GL-5.

There are stories on the internet about "synchornizer corrosion" from GL-5, but I have yet to see any documented evidence of synchronizer corrosion on these 50-year old transmissions, some of which might still have the original factory fill oil in them. It's amazing to me that guys believe all these stories without a shred of evidence.

I am aware that there is some evidence that GL-5 may cause "yellow metal" corrosion at very high temperatures - on the order of 250F or above, but it would be rare for the oil in the transmission to exceed 200F - maybe in serious road racing in hot weather. It appears that some oil marketers are hyping this issue to promote their products, but I think it's bunk!

GL-5 has an EP additive that is absolutely necessary for the hypoid gear set in the axle. GL-4 lacks this additive and GL-4 is the typical spec for modern manual transmissions and transaxles that don't contain hypoid gears. Modern Corvettes have a sort of "transaxle", but the axle and transmission parts of the unit are isolated. They each have their own oil supply - GL-5 in the axle and GL-4 in the transmission.

The trend toward "lighter" manual transmission oils started with new designs in the seventies. Many speced ATF, which has a SAE gear oil viscosity range of 70W-75 with a GL-4 rating. This proved inadequate in some cases, which started a trend to synthetic based 75W-90 GL-4s. Since the EP additive is only necessary for hypoid gears, it follows that GL-4 might be okay for vintage transmissions that specified Mil-L-2105, but I am aware of no long term durability tests that support this conclusion, so my recommendation is to stick with GL-5 as there may be detail internal design differences in modern transmissions that make them compatible with GL-4.

If you have a Positraction axle, you will also need the anti-chatter additive.

Duke

Duke, I have used 50w motor oil in manual transmissions and had quite a bit of success.