Redline MTL versus stock Mazda 75W80 GL4 transmission oil / gear lube

[nickmanns]

Hi,

I own a CX-5, 6MT from 2017. Since a few weeks I have bad shifts. I recently replaced the transmission fluid at 50k kilometers at my Mazda dealer. So I guess they put in the original Mazda 75W80 GL4 oil. It did not result in much better shifting. Especially when cold, the shifting is quite hard. Gear cables are already adjusted, master/slave cilinder and engine mounts show no issues.

I read a lot of good things about Red Line MTL (which should be 75W80 GL4 too). Who has experienced improved shifting with Red Line, compared to the stock Mazda gearbox oil for the CX-5 KF / Skyactiv MT gearbox?

 

[yrwei52]

Hi,

I own a CX-5, 6MT from 2017. Since a few weeks I have bad shifts. I recently replaced the transmission fluid at 50k kilometers at my Mazda dealer. So I guess they put in the original Mazda 75W80 GL4 oil. It did not result in much better shifting. Especially when cold, the shifting is quite hard. Gear cables are already adjusted, master/slave cilinder and engine mounts show no issues.

I read a lot of good things about Red Line MTL (which should be 75W80 GL4 too). Who has experienced improved shifting with Red Line, compared to the stock Mazda gearbox oil for the CX-5 KF / Skyactiv MT gearbox?

So you changed transmission gear lube because of the bad shifts, or you started having bad shifts after the gear lube change? Can you describe in more detail what do you mean by bad shifts? Hard to get into the 1st gear at the stop、difficulty to shift into reverse、or hard to shift into all gears、 etc.?

 

[nickmanns]

Hi,

You're right, details were not there. Indeed I replaced the transmission oil because I got bad shifts. I hoped replacing the oil improved shifting, as all other stuff was checked and OK (gear cable, clutch, motor mounts). Some of the time the shifts are OK and smooth, next it is hard to shift. It applies to all gears including the reverse. So I am basically wondering if redline mtl could smoothen things compared to the Mazda oem oil, or if it would not make much of a difference.

 

[yrwei52]

Hi,

You're right, details were not there. Indeed I replaced the transmission oil because I got bad shifts. I hoped replacing the oil improved shifting, as all other stuff was checked and OK (gear cable, clutch, motor mounts). Some of the time the shifts are OK and smooth, next it is hard to shift. It applies to all gears including the reverse. So I am basically wondering if redline mtl could smoothen things compared to the Mazda oem oil, or if it would not make much of a difference.

IMO it’s a good sign if your hard shifts are from all gears, but intermittent. This means either the culprit is from clutch or gear lube. On the other hand your 2017 CX-5 with only 50,000 km / 31,069 miles is pretty new, you should still have either new-car warranty or powertrain warranty. You should just take your CX-5 to the Mazds dealer and ask them to fix the problem. You mostly likely would get the answer: it’s “normal”, you at least have a couple of service records and complaints logged in Mazda’s system, and in case your transmission failed in the future you have a legit base to hold Mazda responsible to fix the problem.

Remember your factory gear lube in the 6-speed transmission had been working fine initially for the first couple of years. It’s highly unlikely the gear lube suddenly is unstable to cause hard shifts intermittently in such short period of time. Of course you can try a different gear lube such as Red Line MTL and see. But I wouldn’t rule out your Mazda dealer could use something which isn’t OEM or wrong type (check your invoice) on gear lubricant when they did the gear lube change.

 

[nickmanns]

The Mazda dealer indeed told me the shifting is just like any other skyactive Mazda. That is what they always do it seems.

The transmission oil was changed for the 1st time now. And before and after the transmission oil change shifting is hard. So I personally don't think they refilled it with the wrong or different than OEM Mazda fluid. I mean that the factory filled fluid gave me hard shifts as well.

So the complaint is now known at the Mazda dealer, but they cannot find anything wrong or broken now. The logged complaint should help me when it does get even worse or breakdown, but it at the moment lowers my driving pleasure.

Will anyhow wait swapping the transmission oil again. But if transmission oil is swapped next time, I am doubting to take red line or again the oem fluid. I still have some hope that red line is even better than the Mazda oem stuff.

 

[yrwei52]

The Mazda dealer indeed told me the shifting is just like any other skyactive Mazda. That is what they always do it seems.

The transmission oil was changed for the 1st time now. And before and after the transmission oil change shifting is hard. So I personally don't think they refilled it with the wrong or different than OEM Mazda fluid. I mean that the factory filled fluid gave me hard shifts as well.

So the complaint is now known at the Mazda dealer, but they cannot find anything wrong or broken now. The logged complaint should help me when it does get even worse or breakdown, but it at the moment lowers my driving pleasure.

Will anyhow wait swapping the transmission oil again. But if transmission oil is swapped next time, I am doubting to take red line or again the oem fluid. I still have some hope that red line is even better than the Mazda oem stuff.

From my experience on manual transmission the gear lube would last almost forever and it doesn’t need change often. From all the MT vehicles I’ve owned mostly VW’s, I had never changed the gear lube as there’s no maintenance schedule, and the shifting had always been fine. The key in you case is the shifting was fine when new (I assumed until you say it differently), but within short period of time and thousands of miles, the shifting behavior has changed. This means something has degraded. I doubt the OEM fluid would degrade this fast which had affected your shift. But when this happens, the simplest way is to change the gear lube, even with a different brand. If I were you I’d try Red Line MTL 75W-80 as it should be easy, and I can do this by myself. And I can find out if a different lube could really improve the shifting in my case.

Sometimes if the shifting doesn’t improve after the gear lube change with OEM like your case, I’d even suspect if the dealer actually changed the fluid ⋯

Keep in mind that others are fine on manual transmission with OEM gear lube on their CX-5. We have to think why yours is different?

 

[nickmanns]

Keep in mind that others are fine on manual transmission with OEM gear lube on their CX-5. We have to think why yours is different?

Thanks again for your answers. You really have a strong point there. Guess I am a bit blinded to think the gear lube could improve the shifting, while it could also be another issue causing my hard shifting. Remaining options in my opinion are then only something with the clutch or a defect in the gear cable. I wouldnt expect an issue with the clutch yet in a car from 2017, but who knows. The master and slave cilinder could be having a small defect, or could air in the brake/clutch fluid cause the hard shifts ? Adjustment of the gear cable is done, transmission oil is fresh. Guess I could start asking the dealer first to bleed the brake fluid and check the master and slave cilinder... The master cilinder at the clutch pedal does make some noise but guess its the springs that make the noise.

 

[yrwei52]

Thanks again for your answers. You really have a strong point there. Guess I am a bit blinded to think the gear lube could improve the shifting, while it could also be another issue causing my hard shifting. Remaining options in my opinion are then only something with the clutch or a defect in the gear cable. I wouldnt expect an issue with the clutch yet in a car from 2017, but who knows. The master and slave cilinder could be having a small defect, or could air in the brake/clutch fluid cause the hard shifts ? Adjustment of the gear cable is done, transmission oil is fresh. Guess I could start asking the dealer first to bleed the brake fluid and check the master and slave cilinder... The master cilinder at the clutch pedal does make some noise but guess its the springs that make the noise.

Or just replace the brake fluid with fresh one and see. Make sure the mechanic knows you have a clutch and they need to bleed the clutch / salave cylinder too if there’s a bleeding valve just for that. Or you may get fresh brake fluid for brake system, but left old fluid in clutch / salave cylinder which defeats the purpose for you. If you still have newvcar warranty, you should try to report the problem again before the warranty is up. This’s to protect yourself, in case something goes wrong in the future. And in your case, the repair could be costly.

 

[rjdee2]

I doubt this will help you due to time, less than perfect memory and the fact I have no resolution for hard shifting. My take: it's a less durable transmission design but I've driven it hard and have loaded and towed more than I probably should have with it.
I have a 13 MT, purchased May 2012, w 190k miles on it. At about 70-80k (5 ish years ago) is replaced the gear lube with Redline. I was getting tough shifts esp 1->2 and occasional downshifts to 1. I can't recall if I noticed a significant difference w a change in fluid. Shortly thereafter (6 months?) the transmission synchros went and I replaced it w a used tranny from a wreck since it was cheaper and faster to source than something from Mazda. I think the damage had already been done and Redline wasn't the cause. The replacement transmission had 20k on it, I had ~85-90 on the chassis when it was installed and have 190k now so 120k on this transmission. Last fall I had the gear lube replaced by my indy shop. Currently getting hard shifts which have been gradually getting worse. Now I'm finding its usually 3rd gear is stiff and requires more effort. Original clutch and I get some shudder on colder mornings so I'll need to decide if I want to replace that or just drive it until it won't go any longer.

 

[nickmanns]

Update. I changed to RedLine MTL now in my CX-5 KF. Only very slight improvement in shifting behavior compared to the OEM Mazda transmission fluid. Driven only short amount of miles, so might still change?

Gear cables adjusted and greased. I still believe shifting could be smoother, but seems further adjustments are not possible. Will keep you posted on how things are doing after more miles.