Manual Transmission in cold temps

[Scaroline]

Did anyone change the transmission fluid to anything other than the OEM fluid? I live in Boston and drive in the city for a significant amount of time so it takes a while for everything to warm up. The 1-2 shift is very hard when cold unless I double clutch—then its very smooth— or if I shift at around 4000 rpm (I kind of got fed up with the being extra delicate with the shift rpm and shifted later which lead to me discovering that it shifts very well at high RPMs) . I don't really take the car to a track so I don't mind if the fluid isn't the absolute best for the track but rather something that will make the shifts at 2500-3000 smoother. Also realistically speaking, what's the chance of a dealer finding out about the fluid change and voiding warranty if it's done outside.

 

[rubberduck]

I think the choices are Tremec HP-MTF & Redline D4. Personally I would try the Redline, I’ve had good luck with their other MT fluids.

 

[BimmerFan]

They are not going to void your warranty unless the transmission fails, which is unlikely with a fluid that meets specs.

I've heard good things about redline, and I'll be interested if either choice helps you.

 

[BKC1]

The proper mixture is 3 qts Redline D4 ATF + 1 qt Redline MTL 75W80 GL-4.

You should not use ATF straight regardless of brand; it's too slippery and doesn't support proper syncho engagement. You'll find that the ATF+MTL mixture is thicker and makes the synchros sluggish for the first 10-15 minutes at 30°F and below, but it will shift well. You'll feel the added drag until it warms up. At higher temperatures it's a significant upgrade--the notchiness will be reduced and your shifts will be faster and easier.

• Dextron III Viscosity, cSt: 35.55 at 40°C, 7.77 at 100°C
• Redline D4 ATF Viscosity, cSt: 35.4 at 40°C, 7.5 at 100°C
• Redline 75W-80 Viscosity, cSt: 50.8 at 40°C, 10.4 at 100°C

When shifting in anger at 7000 RPM, there's probably nothing better than D4 ATF+MTL. I have 10 years racing T-56 and TR-6060 transmissions with this mixture. The older enthusiasts I learned about this from have been using this much longer on the track and swear by it (e.g. 90's and 00's era Corvettes, Camaros, etc).

In case anyone asks, I am aware of the Tremec HP-MTF fluid but have not tried it. I believe it leverages the principles behind the D4 ATF + MTL mixture, but it is optimized for very high temperature operation. You can see that in the viscosity specs--I would not use this on a daily driven car (it's thicker than straight MTL):

• Tremec HP-MTF Viscosity, cSt: 71.6 at 40°C, 12.1 at 100°C

One problem with running thicker oil on a daily driver is that it's slow to get up to temperature; it's not until oil thins out that it can get into all the crevices and micro-textured surfaces and really take on heat. That's why you see the oil temp climbing slowly on your car for the first 50 degrees; the next 50 degrees takes half as long.

The optimal ratio of ATF to MTL changes as the transmission gets older and the synchros wear out; very worn T-56 and TR-6060s (e.g. 250k miles or a lot of hard launches) require a 50:50 ratio of ATF and MTL. If you're unsure about the optimal ratio, start low. After draining, put 3 qts D4 ATF in, and then pour as much of the 1 qt MTL 75W80 GL-4 as you can before fluid starts running out of the fill hole (~0.85 qt). Then drive in the cold and take notes.

The next time you change the oil, you can increase the ratio of MTL if you want. I've found that 1 in 5 people don't like the cold weather performance and should reduce the MTL to 0.5 qt; the other 4 aren't bothered by it. 5 out of 5 love the shifting performance--I've never heard someone say they didn't notice a significant improvement.

 

[Scaroline]

The proper mixture is 3 qts Redline D4 ATF + 1 qt Redline MTL 75W80 GL-4.

You should not use ATF straight regardless of brand; it's too slippery and doesn't support proper syncho engagement. You'll find that the ATF+MTL mixture is thicker and makes the synchros sluggish for the first 10-15 minutes at 30°F and below, but it will shift well. You'll feel the added drag until it warms up. At higher temperatures it's a significant upgrade--the notchiness will be reduced and your shifts will be faster and easier.

• Dextron III Viscosity, cSt: 35.55 at 40°C, 7.77 at 100°C
• Redline D4 ATF Viscosity, cSt: 35.4 at 40°C, 7.5 at 100°C
• Redline 75W-80 Viscosity, cSt: 50.8 at 40°C, 10.4 at 100°C

When shifting in anger at 7000 RPM, there's probably nothing better than D4 ATF+MTL. I have 10 years racing T-56 and TR-6060 transmissions with this mixture. The older enthusiasts I learned about this from have been using this much longer on the track and swear by it (e.g. 90's and 00's era Corvettes, Camaros, etc).

In case anyone asks, I am aware of the Tremec HP-MTF fluid but have not tried it. I believe it leverages the principles behind the D4 ATF + MTL mixture, but it is optimized for very high temperature operation. You can see that in the viscosity specs--I would not use this on a daily driven car (it's thicker than straight MTL):

• Tremec HP-MTF Viscosity, cSt: 71.6 at 40°C, 12.1 at 100°C

One problem with running thicker oil on a daily driver is that it's slow to get up to temperature; it's not until oil thins out that it can get into all the crevices and micro-textured surfaces and really take on heat. That's why you see the oil temp climbing slowly on your car for the first 50 degrees; the next 50 degrees takes half as long.

The optimal ratio of ATF to MTL changes as the transmission gets older and the synchros wear out; very worn T-56 and TR-6060s (e.g. 250k miles or a lot of hard launches) require a 50:50 ratio of ATF and MTL. If you're unsure about the optimal ratio, start low. After draining, put 3 qts D4 ATF in, and then pour as much of the 1 qt MTL 75W80 GL-4 as you can before fluid starts running out of the fill hole (~0.85 qt). Then drive in the cold and take notes.

The next time you change the oil, you can increase the ratio of MTL if you want. I've found that 1 in 5 people don't like the cold weather performance and should reduce the MTL to 0.5 qt; the other 4 aren't bothered by it. 5 out of 5 love the shifting performance--I've never heard someone say they didn't notice a significant improvement.

Thank you for your reply. I wanted to ask if you know what the stock fluid is and what it’s viscosity is compared to the fluids you listed here.

 

[thefleshrocket]

I haven't touched the trans fluid in my 5BW, which has ~3K miles on it, but I just changed the trans fluid in my new-to-me 2017 C7 Z06, which has 18K on it. I used four quarts of Redline D4 as is typically recommended by the Corvette community. Cold performance is better--previously, when I would sometimes engage first gear, if I didn't give it a firm push, it might pop out of gear as soon as I engaged the clutch. After 100ish miles with the D4, it hasn't done it. The other gears are smoother when cold, too. The Vette is a TR6070 (7-speed) compared to the TR6060 in the 5BW, so not exactly apples to apples.

 

[Orange Whip]

The proper mixture is 3 qts Redline D4 ATF + 1 qt Redline MTL 75W80 GL-4.

You should not use ATF straight regardless of brand; it's too slippery and doesn't support proper syncho engagement. You'll find that the ATF+MTL mixture is thicker and makes the synchros sluggish for the first 10-15 minutes at 30°F and below, but it will shift well. You'll feel the added drag until it warms up. At higher temperatures it's a significant upgrade--the notchiness will be reduced and your shifts will be faster and easier.

• Dextron III Viscosity, cSt: 35.55 at 40°C, 7.77 at 100°C
• Redline D4 ATF Viscosity, cSt: 35.4 at 40°C, 7.5 at 100°C
• Redline 75W-80 Viscosity, cSt: 50.8 at 40°C, 10.4 at 100°C

When shifting in anger at 7000 RPM, there's probably nothing better than D4 ATF+MTL. I have 10 years racing T-56 and TR-6060 transmissions with this mixture. The older enthusiasts I learned about this from have been using this much longer on the track and swear by it (e.g. 90's and 00's era Corvettes, Camaros, etc).

In case anyone asks, I am aware of the Tremec HP-MTF fluid but have not tried it. I believe it leverages the principles behind the D4 ATF + MTL mixture, but it is optimized for very high temperature operation. You can see that in the viscosity specs--I would not use this on a daily driven car (it's thicker than straight MTL):

• Tremec HP-MTF Viscosity, cSt: 71.6 at 40°C, 12.1 at 100°C

One problem with running thicker oil on a daily driver is that it's slow to get up to temperature; it's not until oil thins out that it can get into all the crevices and micro-textured surfaces and really take on heat. That's why you see the oil temp climbing slowly on your car for the first 50 degrees; the next 50 degrees takes half as long.

The optimal ratio of ATF to MTL changes as the transmission gets older and the synchros wear out; very worn T-56 and TR-6060s (e.g. 250k miles or a lot of hard launches) require a 50:50 ratio of ATF and MTL. If you're unsure about the optimal ratio, start low. After draining, put 3 qts D4 ATF in, and then pour as much of the 1 qt MTL 75W80 GL-4 as you can before fluid starts running out of the fill hole (~0.85 qt). Then drive in the cold and take notes.

The next time you change the oil, you can increase the ratio of MTL if you want. I've found that 1 in 5 people don't like the cold weather performance and should reduce the MTL to 0.5 qt; the other 4 aren't bothered by it. 5 out of 5 love the shifting performance--I've never heard someone say they didn't notice a significant improvement.

Would the Tremec HP-MTF be a good option for a car that lives in Phoenix? We rarely get below 50, and most of the year is between 60 and 80.

Last July we had 31 days straight where the low was above 90F and the high was just under 120F.

 

[Dirkbg]

Maybe someone attending Spring Mountain soon can ask them what they are using. Similar environment to Phoenix, but maybe a little different for those of us in winter states, and not tracking 100% of the time.

 

[rubberduck]

Would the Tremec HP-MTF be a good option for a car that lives in Phoenix? We rarely get below 50, and most of the year is between 60 and 80.

Last July we had 31 days straight where the low was above 90F and the high was just under 120F.

I’m also in Southern Arizona and my transmission temp has gone above 200F occasionally in the summer in stop-and-go traffic. I was wondering if that was normal. How high does yours get?

 

[jbawden]

Maybe someone attending Spring Mountain soon can ask them what they are using. Similar environment to Phoenix, but maybe a little different for those of us in winter states, and not tracking 100% of the time.

My understanding is the only deviation from OEM is the brake fluid (they use ATE 200).

 

[Orange Whip]

I’m also in Southern Arizona and my transmission temp has gone above 200F occasionally in the summer in stop-and-go traffic. I was wondering if that was normal. How high does yours get?

I've only had mine for two weeks. Trying to be proactive in planning for hotter temps.