How to change manual transmission fluid

Where DIYs with photos live. Please start new topics in DIY section. Completed DIYs are moved here for clutter control and quicker reference.
User avatar
redmed
Posts: 492
Joined: Fri Oct 01, 2010 12:56 pm
Location: Michigan

I took a tour of local auto parts stores yesterday looking for synthetic manual transmission oil. What I found was surprising. Most stores had a very limited selection. One store had only one non-synthetic manual transmission oil! Of the synthetic oil I found all where listed as GL-4 & GL-5. I take this as the oil contains sulfur that will harm the soft metals in the transmission. In my research I found only two manufactures that produce synthetic GL-4 oils Amsoil and Redline. Neither was found in any of the stores. I called a auto parts store I have gone to for years. I now live a hours drive away. They have both Redline MT-90 and MTL in stock. Boy, I miss that store. I also have a Amsoil dealer within 5 miles of me. Based on the recommendation of KuroNekko and many others, some stating that they like Redline over Amsoil. I'm going to take a trip to my old favorite auto parts store and pick up some Redline MT-90 for my Toyota Corolla and Redline MTL for my Kizashi. The Corolla wants 75-90 so it gets the MT-90. MTL is right on spec for the Kizzy. This way I get to try both oils. I'm also going to ask what shock absorbers they have for the Kizashi. I would not be surprised they have something other than the KYB's shocks that are the only shocks I found available until now.
64 Galaxie 68 Olds 442 65 Impala 70 VW Bug
74 Nissan B210 66 Chevelle 73 Olds 98 71 C20
75 Monza 82 Escort 75 E150 75 Civic 76 Accord
86 Escort 87 Taurus 83 Chevy G20 85 Ranger 4x4
93 F250 4x4 95 Silhouette 95 LHS 03 Corolla 10 Kizashi S MT
17 Sienna
User avatar
KuroNekko
Posts: 5170
Joined: Wed Aug 15, 2012 5:08 pm
Location: California, USA

redmed wrote:I took a tour of local auto parts stores yesterday looking for synthetic manual transmission oil. What I found was surprising. Most stores had a very limited selection. One store had only one non-synthetic manual transmission oil! Of the synthetic oil I found all where listed as GL-4 & GL-5. I take this as the oil contains sulfur that will harm the soft metals in the transmission. In my research I found only two manufactures that produce synthetic GL-4 oils Amsoil and Redline. Neither was found in any of the stores. I called a auto parts store I have gone to for years. I now live a hours drive away. They have both Redline MT-90 and MTL in stock. Boy, I miss that store. I also have a Amsoil dealer within 5 miles of me. Based on the recommendation of KuroNekko and many others, some stating that they like Redline over Amsoil. I'm going to take a trip to my old favorite auto parts store and pick up some Redline MT-90 for my Toyota Corolla and Redline MTL for my Kizashi. The Corolla wants 75-90 so it gets the MT-90. MTL is right on spec for the Kizzy. This way I get to try both oils. I'm also going to ask what shock absorbers they have for the Kizashi. I would not be surprised they have something other than the KYB's shocks that are the only shocks I found available until now.
I'd go with MTL for the Kizashi as well given you live in MI and probably see snot-freezing temperatures in the winter. Keep us posted on how it affects the MT shifting.

I'd be very surprised if you find shocks for the Kizashi other than KYB Excel-Gs which are the OE shocks. The only other shocks I know of that were made for the Kizashi are the German KWs. They also happen to cost $1500 as a suspension set.
2011 Suzuki Kizashi Sport GTS 6MT (Black)
bootymac
Posts: 1602
Joined: Fri Jul 19, 2013 1:04 am

A manual Corolla? Must be a unicorn (or AE86).

And yeah, if there were any other shocks, Rock Auto would have it listed
murcod
Posts: 2279
Joined: Fri Aug 03, 2012 12:03 pm
Location: Australia

KuroNekko wrote: I'd be very surprised if you find shocks for the Kizashi other than KYB Excel-Gs which are the OE shocks.
The same manufacturer. Suzuki lists different shock part numbers for Sports (or GTS/ SLS) vs "normal" Kizashi models; the KYB shock listing is "one size fits all".

MTL would be perfect in any climate as it matches the factory recommended spec. I'd even go for that weight where I live (rarely gets to 0 C and hits up to 45 C in Summer). The Kizashi box isn't exactly renowned for it's smooth shifting characteristics, so thinner should be better.
David
User avatar
KuroNekko
Posts: 5170
Joined: Wed Aug 15, 2012 5:08 pm
Location: California, USA

murcod wrote:
KuroNekko wrote: I'd be very surprised if you find shocks for the Kizashi other than KYB Excel-Gs which are the OE shocks.
The same manufacturer. Suzuki lists different shock part numbers for Sports (or GTS/ SLS) vs "normal" Kizashi models; the KYB shock listing is "one size fits all".

MTL would be perfect in any climate as it matches the factory recommended spec. I'd even go for that weight where I live (rarely gets to 0 C and hits up to 45 C in Summer). The Kizashi box isn't exactly renowned for it's smooth shifting characteristics, so thinner should be better.
Yes, it's true that the Sport models have different shock parts # from Suzuki, but the very manufacturer of these shocks don't differentiate them. The question is whether there is actually any difference. I've looked on KYB's site before and found no shock other than the same Excel-Gs offered for all Kizashis regardless of MY or trim. In essence, they didn't show that the Sport models used a different Excel-G shock or the higher tier KYB Gas-A-Just shocks. In fact, KYB's list shows these aren't available for the Kizashi.

In essence, it's only Suzuki themselves who claim there is a difference in the shocks. Their very OE part supplier seems to indicate a different story. Also, all the Kizashi Sport product descriptions I've ever read state that the Sport models have 18 inch lightweight wheels and a 10mm lowered suspension height (from the springs, I presume). I've never read anything stating the actual shocks were different.

About the only ones who can set this matter straight is Suzuki themselves.

About the MT fluid viscosity:
I believe thicker is better in hotter temperatures, not thinner. Thinner is the winner in colder temps. This is the case with motor oils and every lubricant for automobiles I know about. Also, I disagree about your point on; "The Kizashi box isn't exactly renowned for it's smooth shifting characteristics, so thinner should be better."
It's my belief and experience that thicker is better when you want smoother because it buffers things better. I agree that the shifter in the Kizashi isn't smooth, but that's the very reason why I went with the thicker MT-90. Consequently, it smoothed out shifting and gear engagement considerably. It's a vast improvement in shift feel over the factory fill which is a semi-synthetic 75W-80.

Keep in mind none of this viscosity talk really matters. Suzuki states all viscosities (75W-80, 75W-85, and 75W-90) are acceptable in all temperature ranges. The reason to use different weights would then hinge more on user preference and extreme temperatures. For hotter climates, it's the thicker weight you'd want to use.
I used my MT-90 in -15 C temperatures last winter. Yeah, it was a bit heavy, but nothing to be concerned about. At -30 C (-22 F), I'd want the thinner 75W-80/MTL. At 45 C (113 F), I'd want the thicker 75W-90/MT-90.

All this being said, any of these weights would be suitable and that's according to Suzuki. They just recommend 75W-80 as the optimal weight.
2011 Suzuki Kizashi Sport GTS 6MT (Black)
murcod
Posts: 2279
Joined: Fri Aug 03, 2012 12:03 pm
Location: Australia

Thicker isn't better for synchro operation- which directly affects shift quality (grating when changing up.) I've had my oil changed under warranty for 2nd gear not being the best when shifting - and not just in cold conditions. I know other people on here have also made similar comments regarding 2nd gear.

Here's an extract from an article on transmission fluids:
Transmission Fluid Requirements
Viscosity
The viscosity or fluid thickness is the most important characteristic of the transmission lubricant. It must be high enough to support the expected loads encountered by the gears and still be able to readily flow, even at low ambient temperatures, between the gear teeth and into bearing spaces. It also has to be able to easily flow into the “synchro” units and not impede their operation by being too thick. In addition, it has to provide the necessary cooling for the transmission.
It is estimated that only 2% to 3% of the lubricant is required for lubrication and the remaining 97% to 98% is required for cooling. Lubricants exhibit thickening under load and this thickening or increase in viscosity assists in ensuring that they are able to accommodate the high loads generated by the meshing gears.
from http://www.nulon.com.au/pdf/FS118%20-%2 ... ubricants/

75W80, 75W85, 75W90 are all listed on the viscosity chart, but it specifically says:
NOTE:
It is highly recommended to use “SUZUKI GEAR OIL 75W-80”.
So 75W80 would be the factory fill and going thicker could cause sychroniser issues. I certainly wouldn't be going for thicker oil in my gearbox.

I'm also a bit puzzled by this earlier comment:
KuroNekko wrote:... Also, MT-90 didn't make shifting in cold weather all that much worse than the factory fill....
:?:

Without wanting to turn this into a shock absorber thread, you've assumed that the aftermarket KYB shocks and Suzuki OEM shocks are all identical with their internal valving. Lowered suspension (with firmer springs) would normally dictate the requirement of different shock valving; given the two different Suzuki part numbers it would be likely that is exactly what Suzuki has done. Factory OEM spec shocks are often valved differently to what the shock manufacturer themselves sells as aftermarket parts - even when both are made by the same company.
David
bootymac
Posts: 1602
Joined: Fri Jul 19, 2013 1:04 am

Here's a story to wrap your head around. VW specifies 75w90 but the OEM fluid's viscosity at 100C is only 6.3cSt compared to the following:

10.6 = Redline MTL 70w80
13.8 = Amsoil MTG 75w90
15.2 = Motul Gear 300 75w90
15.6 = Redline MT-90 75w90
15.0 = Elf Tranself Synthese FE 75w90
16.7 = Motul MOTYLGEAR 75w90

People have been using MT90 and reported notchy shifting and worse grinding. I replaced my OEM fluid with Pennzoil synthetic 75w90 and get embarrassing grinds when I shift into 2nd too quickly.

Thinner does seem to result in smoother shifting. A lot of tuners swore by GM (Pennzoil) Synchromesh and its 9.08cSt viscosity. Other brands have similar fluids (eg RP Synchromax, 7.7cSt)
User avatar
KuroNekko
Posts: 5170
Joined: Wed Aug 15, 2012 5:08 pm
Location: California, USA

murcod wrote:Thicker isn't better for synchro operation- which directly affects shift quality (grating when changing up.) I've had my oil changed under warranty for 2nd gear not being the best when shifting - and not just in cold conditions. I know other people on here have also made similar comments regarding 2nd gear.

Here's an extract from an article on transmission fluids:
Transmission Fluid Requirements
Viscosity
The viscosity or fluid thickness is the most important characteristic of the transmission lubricant. It must be high enough to support the expected loads encountered by the gears and still be able to readily flow, even at low ambient temperatures, between the gear teeth and into bearing spaces. It also has to be able to easily flow into the “synchro” units and not impede their operation by being too thick. In addition, it has to provide the necessary cooling for the transmission.
It is estimated that only 2% to 3% of the lubricant is required for lubrication and the remaining 97% to 98% is required for cooling. Lubricants exhibit thickening under load and this thickening or increase in viscosity assists in ensuring that they are able to accommodate the high loads generated by the meshing gears.
from http://www.nulon.com.au/pdf/FS118%20-%2 ... ubricants/

75W80, 75W85, 75W90 are all listed on the viscosity chart, but it specifically says:
NOTE:
It is highly recommended to use “SUZUKI GEAR OIL 75W-80”.
So 75W80 would be the factory fill and going thicker could cause sychroniser issues. I certainly wouldn't be going for thicker oil in my gearbox.
All very interesting. However, I wonder why the factory fill was inferior to the performance MT-90 provided. Regardless, I agree that sticking to the recommended viscosity of 75W-80 is best. However, I just don't see enough of a reason to dump my MT-90 if it's A) still acceptable according to Suzuki and B) empirically offers better shifting than the factory fill, and C) is a better product than the factory fill.
I'll try Red Line MTL next time since this discussion has got me curious.
murcod wrote:I'm also a bit puzzled by this earlier comment:
KuroNekko wrote:... Also, MT-90 didn't make shifting in cold weather all that much worse than the factory fill....
:?:
MT-90 obviously has a higher viscosity than other products of thinner weights like 75W-80. Bootymac revealed data that showed MT-90 has a flow characteristic of 15W-40 when compared to motor oil. This indicates that MT-90 is rather thick compared to something like MTL and not as ideal in cold weather than a thinner gear oil. However, empirically, MT-90 wasn't all that different in cold weather performance than the factory fill. Last winter was the coldest winter I've experienced as the Mid-Atlantic USA got a good bit of the "Polar Vortex". Despite the record low temperatures (it was the coldest the region had been in over 100 years), my shifting performance didn't suffer too much and wasn't significantly worse than the factory fill (Suzuki's 75W-80) the winter before that. That's what I meant.
murcod wrote:Without wanting to turn this into a shock absorber thread, you've assumed that the aftermarket KYB shocks and Suzuki OEM shocks are all identical with their internal valving. Lowered suspension (with firmer springs) would normally dictate the requirement of different shock valving; given the two different Suzuki part numbers it would be likely that is exactly what Suzuki has done. Factory OEM spec shocks are often valved differently to what the shock manufacturer themselves sells as aftermarket parts - even when both are made by the same company.
I see what you are saying about the shocks. The problem is that there is absolutely no indication of this from the very company that made the two different shocks (Kizashi vs. Kizashi Sport shocks). All KYB states is that one shock fits all. While I understand your argument of Suzuki OEM vs. KYB aftermarket, I'm puzzled why KYB wouldn't sell a Kizashi Sport-spec'd shock in the aftermarket. From what I'm seeing, one is forced to buy a replacement shock for the Kizashi Sport from the dealer and simply trust that it's different from the non-Sport shock. That trust results in a 300% increase in cost from a KYB aftermarket to a Suzuki OE part.
2011 Suzuki Kizashi Sport GTS 6MT (Black)
bootymac
Posts: 1602
Joined: Fri Jul 19, 2013 1:04 am

I spent some time researching MT fluids (the things I do when I'm bored... :facepalm:) and the consensus is that thinner fluids provide much better shifting. A TON of enthusiasts from all makes have great experiences with synchromesh fluids, which are characterized with a viscosity at 100C of ~9cSt. Smoother, less resistant shifting in all temperatures and all grinding issues were eliminated with synchromesh fluids. Examples include:

- GM/AC Delco (9.1cSt):
- Pennzoil (9.1cSt): http://shop.advanceautoparts.com/p/penn ... /7070062-P
- Valvoline (8.8cSt): http://www.oreillyauto.com/site/c/detai ... &ppt=C0207
- Royal Purple (7.7cSt):
- Amsoil (9.7cSt): http://www.amsoil.com/shop/by-product/t ... uid-5w-30/
- Redline MTL (10.4cSt):

GM/AC Delco also have a synthetic synchromesh fluid with friction modifiers. This fluid is blended with Group V chemicals that further improve with cold weather performance. Honda guys love this stuff:

I compiled most of the common gear oils for reference:
User avatar
redmed
Posts: 492
Joined: Fri Oct 01, 2010 12:56 pm
Location: Michigan

KuroNekko wrote: I chose MT-90 for many of the reasons you guessed.
First, I've used MT-90 before with great results. I used it in my Mazda3 that I drove before the Kizashi. Before Redline MT-90, I had Royal Purple Max Gear which also was a great improvement over the factory fill.
I mainly used Redline MT-90 because it was recommended by Mazda3 owners and even the dealer for the Mazda3. The dealer carried MTL but recommended MT-90 for the smoothest shifting. For that car, MT-90 was the preferred weight. While it may seem irrelevant for the Kizashi, I simply found MT-90 as the preferred Redline manual transmission gear oil even for other cars when researching online.
Bootymac's spreadsheet confirms his thought that thinner fluids provide better shifting, based on your experience between Royal Purple Max Gear (17.5) vs MT-90 (15.6) and strengthens my decision to use MTL (10.4).
64 Galaxie 68 Olds 442 65 Impala 70 VW Bug
74 Nissan B210 66 Chevelle 73 Olds 98 71 C20
75 Monza 82 Escort 75 E150 75 Civic 76 Accord
86 Escort 87 Taurus 83 Chevy G20 85 Ranger 4x4
93 F250 4x4 95 Silhouette 95 LHS 03 Corolla 10 Kizashi S MT
17 Sienna
Post Reply