What's best for a bit more baulk/blocker ring friction thicker or thinner gearbox oil? I've tried redline 75w80 and 90 with not much difference 1st to 2nd is still notchy
Thicker or thinner gearbox oil
- Thread starter Chadders99
- Start date
What car, what exact engine and transmission?
EDIT: you already have a thread:
https://bobistheoilguy.com/forums/threads/75w90-or-75w80-for-notchy-2nd.311201/
(forum software suggested this as 'similar thread')
EDIT: you already have a thread:
https://bobistheoilguy.com/forums/threads/75w90-or-75w80-for-notchy-2nd.311201/
(forum software suggested this as 'similar thread')
I don't think the viscosity matters when they are relatively close. Your transmission might be notchy1 to 2nd regardless of the fluid you use.
You could try The Miata owners favorite, Motorcraft XT-M5-QS. I put it in a VW GTI I once owned and it was great. The Motorcraft fluid is made in Germany, a country where they understand sticks better than the USA. Read the reviews on Amazon.
https://www.amazon.com/Genuine-Ford...+transmision+fluid&qid=1628953782&sr=8-3&th=1
You could try The Miata owners favorite, Motorcraft XT-M5-QS. I put it in a VW GTI I once owned and it was great. The Motorcraft fluid is made in Germany, a country where they understand sticks better than the USA. Read the reviews on Amazon.
https://www.amazon.com/Genuine-Ford...+transmision+fluid&qid=1628953782&sr=8-3&th=1
Whether you go 75W-80 GL-4 or 75W-90 GL-4 does make a difference since the latter is twice as thick both cold and "warm".
So far I'm happiest with both Castrol Syntrans V-FE = Transmax V 75W-80 and Ravenol MTF-2 75W-80 GL-4, but I wouldn't generally recommend them if your transmission is specced for 75W-90 GL-4 as I cannot guarantee wear protection is sufficient. Remember shift quality (and synchro life) and wear protection (bearings and gears) aren't the same, they're actually often contradicting.
So far I'm happiest with both Castrol Syntrans V-FE = Transmax V 75W-80 and Ravenol MTF-2 75W-80 GL-4, but I wouldn't generally recommend them if your transmission is specced for 75W-90 GL-4 as I cannot guarantee wear protection is sufficient. Remember shift quality (and synchro life) and wear protection (bearings and gears) aren't the same, they're actually often contradicting.
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My daughter has a Suzuki SX4 6-speed manual and they have the infamous 2nd gear crunch. Played with various viscosity fluids and blends then settled on Penrite Pro Gear 70W-75 synthetic. Fixed it.
Honda MTF has always worked for me
What does Suzuki spec? Going thinner (most) often helps with shifting, not uncommon at all.
.
I've purchased some oil specified for my car from my local kia dealer parts dept. total traxium duel 9 fe 75w90 only I'm a bit confused as it says its suitable for gl4 gl5 mt1 how can it cover all those I thought gl4 and gl5 are completely different? it's also SAE J2360 which is the highest standard it seems to be shifting better now tho
MolaKule
Staff member
That is because you just filled it with this lube for Hypoid differential and HD gear boxes instead of using a GL-4 Manual Transmission Fluid (MTF).
You may have gearbox wear such that no fluid, in the long-term, will fix it.Total said:
I've been speaking to a Kia master tech and he says that the oil specified by kia for my syncro problem (as it's quite a common problem in kia gearboxes) is traxium 6 75w85 but has been superseded by the traxium 9 75w90 and the guy I spoke to from total says it's fine for yellow metal although its a gl5 .also what I cant understand is why staying with the same grade 75w90 but moving up to a gl5 make shifting feel smoother than when I used redline mt90
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MolaKule
Staff member
Sounds like a temporary fix for a design problem. A thicker oil mostly dampens noises.
Agreed - synchro performance is about friction behaviour rather than viscosity. I had a Honda CRX with a crunchy 5th gear - I tried some fluid changes but in the end the only fix was to fix it.
That traxium sounds like something I'd like to try (currently using mt90), but a quick search seems to show it's not available in the US. So it's OK to use some gl5 gear oils in a manual transmission (Tremec TR6 in my case)? I found the mt90 improved things quite a bit compared to the OE specified ATF, or other manual transmission fluids I tried. However, I don't have to deal with cold temps during any part of the year.
Over the years, with many race cars, street cars and trucks, it's become clear that sufficient viscosity is helpful for a "cushion" effect with sliding gears and helps provide a smooth feel. Motorcycle riders (no syncro's) notice that more viscous oil, or even just an oil change, often leads to less notchy shifting. However, that effect is isolated and different from the typical syncronizer friction related problems of "grinding" while shifting into the chosen gear. If the syncro's can't grab the gear and match it's speed, it can be really notchy or grind. In that case, a lower viscosity can allow the syncro to function normally, where a higher visicosity can keep the components apart long enough to cause annoyance. Drivers notice poor shifting on cold transmissions sometimes.
I agree with cujet, if the shifting is worse when cold there's a good chance thinner fluid works, but if the shifts are bad hot and cold it's not likely a viscosity issue.
Ditto. Installed this oil in my Grand Vitara 4WD 5-spd manual gearbox as an experiment to see how much it improves the shifting, which of course it does very much and the operating temp measures 7°C lower. The Suzuki spec is 75W-85 or 75W-90, same as the SX4 which of course is a full traverse FWD-type transaxle.
I can't see any reason why I can't use a lighter oil than Suzuki specified, especially if I'm not towing and in mild ambient temps, between 8 and 35°C.
My EV single-speed transaxle actually specs a 70W and has a conventional open diff so I don't see why the SX4 diff can't manage that as well.
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75W-90.
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