Transmission fluid replacement

[miranda]

Once again a beginner question. The level of my transmission fluid is getting low, it has been leaking just a little bit over time. I don't want to do damage so i think the time has come to put new fluid in. Having never done anything of that kind, i am wondering if i can do this myself, or bring the car to a shop. I have no idea what kind of fluid is in there now. I read on the forum that some people use Red Line MT90 or red line MTL. can i just refill the fluid, or does the system need to be cleaned out some way? Any tips for beginners are welcome

thanks

sjoerd

 

[John Loftus]

Hi Sjoerd,

Changing the transmission fluid is an easy job but you may need to improvise on the tools to remove the two drain plugs. The gear box has a drain plug with a square recess. I have taken an old 1/2" drive extension (or get a new cheap one from Harbor Freight)and grind it down to size .44" per side). If you have an overdrive, there is a large threaded plug on the bottom which has notches around the perimeter. There is a special tool to unscrew this without causing damage https://www.britishtool.com/servtool.htm but you can also remove this with a pin spanner or by carefully tapping one of the notches with a large punch or by making your own tool. The overdrive drain plug covers a mesh filter and ring magnet that needs to be cleaned thoroughly (paint thinner or lacquer thinner). I and others have used the Redline MT90 and notice smoother shifting and less gearbox noise but it may actually leak more than regular oil. If you have a small leak it shouldn't be a problem .. leaking oil is pretty common with British cars /ubbthreads/images/graemlins/wink.gif Just keep an eye on it and eventually new seals and gaskets can be used to seal things up (but requires gearbox removal). Refilling the gearbox is through the dipstick opening and the capacity for the 6 cylinder gearboxes is 3.45 quarts for the gearbox and .875 quarts for the OD (they share the same oil). I don't recall it taking quite this much to refill though so be careful not to overfill. You don't need to "flush" the system before using the MT90 .. just let it drain (remove the dip stick to let the oil flow better), fit drain plugs and then refill. If you want to try the Redline oil can check the Redline wedsite to find a dealer near you. It's expensive enough without having to pay for shipping!

Cheers,
John

 

[miranda]

Thank you John,
Looks like a nice project for one of these rainy days. If I run into any problems i will post them and seek help again.

sjoerd

 

[RF Thom]

miranda

I talked to the Red Line dealer at Carlisle Import last year. He assured me their MTL was ideal for the Healey O/D trans. I bought 4L and installed it, but I think it is too thin and didn't like the noise / feel of the trans. I've since removed it and returned to a non-detergent SAE # 30 oil [which is OEM spec ] complimented with half bottle of STP which is an elevaled temp viscosity improver. I like the feel / noise of the trans better with this combination. Not sure if their MT90 would be too heavy for this trans.

Regards, Bob

 

[Keoke]

RF Tom, MT 90 Red line seems to be the choice of most of the listers on this forum and MTL has not been suggested for use in the Healey gear box.??----Keoke /ubbthreads/images/graemlins/confused.gif

STP! why didn't you get some good stuff like Lucas Oil Stabilizer.??

 

[Dave Russell]

[ QUOTE ]
miranda
I talked to the Red Line dealer at Carlisle Import last year. He assured me their MTL was ideal for the Healey O/D trans. I bought 4L and installed it, but I think it is too thin and didn't like the noise / feel of the trans. I've since removed it and returned to a non-detergent SAE # 30 oil [which is OEM spec ] complimented with half bottle of STP which is an elevaled temp viscosity improver. I like the feel / noise of the trans better with this combination. Not sure if their MT90 would be too heavy for this trans.
Regards, Bob

[/ QUOTE ]
Hi Bob,
Don't believe everything that "dealers" tell you.

Numbers quoted below are approximate;
RL MTL is a SAE 70W-80 GL-4 gear oil. It has a viscosity equivalent to a SAE 10W-20 motor oil.

RL MT-90 is a SAE 75W-90 GL-4 gear oil. It has a viscosity equivalent to a SAE 15W-50 motor oil.

SAE 30 motor oil has a viscosity equivalent to a 85W gear oil.

You are correct. RL MTL is a bit light for hot climate transmission lube. It might be great in cold climates.

Compared to SAE 30 motor oil, RL MT-90 is thinner at the cold temps & thicker at the hot ones. Better all around. I think that the multi-vis RL MT-90 likely does the same or a better job than SAE 30 plus STP. And to boot, it is thinner at low temps.

Good that there are choices. /ubbthreads/images/graemlins/laugh.gif
D

 

[RF Thom]

Dave

Thanks for the quick refresher on gear oils. I'm going to get out my 2000 copy of the SAE Handbook [ can't believe they still call a four [4] volume 20,000 page manual a handbook ] and do some research. Around '92 the API redefind the Reynolds number values for motor oils [ the spec for a SAE 10W assumed the approx. values of would have been a SAE 7.5W under the previous rating system ] Not sure what happened to the 'three ball test' specification limits.

Thanks Bob

 

[Dave Russell]

Hi Bob,
I was comparing approximate center of the viscosity ranges in SUS at 210 F. for motor oils & SUS at 100 F. for gear oils.
D

 

[Johnny]

Good day sjoerd. I just read a great article on which transmission oil we should be using. The shop backs up their reccommendation with extensive testing which are listed in the article. Just click above under attachment for the article. Bottom line, they reccommend sae 30w non-detergent oil exclusively.

 

[Dave Russell]

Hi Johnny,
Esposito backs up the obvious with reasonable test results for straight grade oils. He briefly mentions synthetics but does not evaluate them.

SAE 30 would have a viscosity of around 450 SUS at 100 degrees F. & 60 SUS at 210 degrees F.

SAE 90 gear oil would have a viscosity of 1000 SUS at 100 F, & 92 SUS at 210 F.

Obviously, the SAE 90 gear oil is much thicker than SAE 30 motor oil at both temperature extremes & would likely cause the OD problems described.

There is another option that gives the best of both worlds, which he did not discuss:

RL MT-90 75W-90 would have a viscosity of 200 SUS at 100 F. & 80 SUS at 210 F.

RL MTL 70W-80 would have a viscosity of 120 SUS at 100 F. & 80 SUS at 210 F.

The RL MTL as compared to SAE 30, is perhaps a bit too thin at lower & intermediate temperatures, especially in worn overdrives, & likely a bit better at high temperatures.

The RL MT-90 is thinner at lower temperatures than SAE 30, much thinner than SAE 90 gear oil, thicker than SAE 30 at high temperatures, a bit thinner than SAE 90 gear oil at high temperatures, & a better all around lubricant.

I suspect that if a really good multi viscosity gear oil had been available when the cars were built, it would have been recommended.

Note: All viscosities quoted are approximate.
D

 

[John Loftus]

I used the Redline MTL in my gearbox because it was recommended by someone who used it and was pleased. The shifting and gearbox noice was noticable improved but I eventually noticed a bit more leakage. I called the factory tech line and was told that they recommend the MT-90 for the Healey gearbox with OD. My car is undergoing restoration but when I refill the gearbox I plan to use the MT-90.

Cheers,
John

 

[dndkk]

I'm confused around the statement on the dipstick...I don't recall seeing one for the trany or am I not looking in the right places..my leaks as well and needs filling...

 

[Keoke]

HI dndkk, I believe John is refering exclusuvely to a Austin Healy gear Box not a Triumph. However, There is a Triumph section on this forum you can use,or clarify which model Healey do you own---Fwiw---Keoke

 

[Dave Russell]

Hi Doug,
Welcome to the forums. You are presently on the Healey forum. The Healeys have a transmission oil dipstick on the front top of the case. Your TR6 likely has a screw in level check plug about midway up the side of the transmission case.
D

 

[kcolas]

I got ointo this thread AFTER changing GB and O/D oil to RL 30w non-detergent. I haven't run the car yet as I'm awaiting the rebuilt brake booster (in another post!), but noticed a big leak under the O/D after a few days of sitting. Naturally, seeing my little puddle, I thought I'd better check the forum. The Red Line oil is very thin. Has anyone used it in the gearbox? /ubbthreads/images/graemlins/confused.gif

 

[Keoke]

HI Kcolas, Yes I agree that the Red line oil is a bit thin and is not happy in my gear box.However, several others on this forum seem to have good results using it.---Fwiw---Keoke

 

[miranda]

Thanks to everybody responding to my question! Since i already bought some RL MT90 i will try it and see how it works. I will let everybody know if i like it or not. Once again i appreciate all the advice

sjoerd

 

[tahoe healey]

I have the leak problem also. The nice thing is that you can tell the difference between it and the engine oil becouse it is yellow. I cannot figure where it is leaking from and the level still seems ok. On the other side of this discussion, I have noticed easier shifting and I think I like the stuff. I was thinking I might try the old standard stuff next time as a test. Before I used Redline, I have no idea how old the fluid was and that may be why Redline seems so much of an improvement. But who knows when that will happen so I'm interested in all your comments. I have always had a scary screem in third gear when climbing on a warm day and I thought Redline would help but it didn't.

 

[Keoke]

/ubbthreads/images/graemlins/savewave.gif
SO TH where do you see the yellow oil out the bellhousing hole or else where???---Keoke