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-   -   Lower Viscosity Oil in Gearbox - Pros and cons? (https://www.team-bhp.com/forum/technical-stuff/99990-lower-viscosity-oil-gearbox-pros-cons.html)

MY Safari has the problem of hard shifts when engine is cold. ITs more pronounced in winters, and this problem has been there forever.
I was wondering whether shifting to a thinner oil, like Power steering oil will solve this problem.
Moreover, I am worried about potential issues.
For example, gearbox oil has 130 degrees boil resistance, definitely power steering oil may lose lubrication properties much early.

Then there is the issue of synchronizers too. Will a thinner oil have higher wear rate?

I can also try and follow a middle path route.
For example current gearbox oil is 75W90. I can probably try a 75W85 which is slightly thinner, but not in Power steering oil territory.

Engine and Gearbox experts, please help!

@tsk1979; You can try a thinner oil, but make sure it is EP even if the current requirement is not. EP will cover a lot of sins, esp. shearing of the oil film.

I was recommended to move to a thinner oil during the winters (like power steering TQ oil) and change back to regular for summers as I faced the same issue as you mention.

Didn't feel comfortable with the idea and then someone recommended a Gear additive that I can't recall right now but it worked awesome. This winter I could change gears quite comfortably thanks to that. Will check about the brand and let you know.

Cheers,
Adi

One additive which a lot of people in the UK swear by is something containing Molybdenum (Liquid Moly or something). All sorts of miracles are claimed for it.

@TSK: I used to have the same problem with my indica Xeta. Gear shifts used to be hard during winter and 1st to 2nd and 3rd to 4th shifts offered a lot of resistance. I used to replace transmission fluid at 20K as recommended but the problem never went away during the 4 years I had it. So what i am saying is that it may just be a TATA trait. therefore, if you can then live with it rather than experimenting with the already fragile white elephant.

Please rename the thread to "Lower Viscosity Oil in Gearbox: Pros & Cons". When I looked at it I thought you were talking about paint thinner. Call me crazy but that is how it looked to me and I found myself asking "what happened to Tanveer?"...lol..

thanks Vikram, I have made the change!

that said, I think I will experiment with a gearbox oil additive rather than looking for a lower viscosity oil.

Hi,
AFAIK, EP is specifically not recommended for gearboxes. Only for hypoids. At least that was the case till a few years back.

Maybe basic lube chemistry has changed recently.

Regards
Sutripta

Tsk, another option you can try is synthetic gear oil.

BTW, the recommended oil for my manual transmission is ATF (auto trans fluid). I switched to synthetic ATF and it helped a little

Hi,
ATF used to come in different types (GM and Ford, and later on, even Chrysler's was also different) and absolutely not interchangeable. Has that changed now? And if it has not, which one is recommended for MTs?

Regards
Sutripta

there seems to be some logic there. my car's manual has this entry in the "lubricants and greases for transmission" section:

molybednum disulphide,lithium-soap based grease, water-resistant N.L.G.I. consistency =2 : MRM 2 : CV joints.

Tutela MRM2

Molybdenum disulfide - Wikipedia, the free encyclopedia

Yes! EP- Extreme pressure is preferred for Hypoids due to the tremendous heat generated due to localized tooth pressures, is this applicable to GB also? How does this EP oil affect the Synchros then?


Dada, good one!

Spike:uncontrol

Hi,
No, actually I don't know. Recently, esp. due to environmental reasons, lot of changes in fuels and lubes. Haven't kept abreast.

What do you think of Moly, (or colloidal graphite) added to lubes?

Regards
Sutripta

Have heard of these (Moss) base being used in various applications, what constituents were leading to environmental pollution?

Spike

^^^
Hi,
Moly was w.r.t. effectiveness/ cost effectiveness, not environmental issues. I mean adding a (very costly) solid lubricant to a liquid.

Regards
Sutripta