Motor oil in manual transmission

[parshisa]

Do you guys have experience running motor oil in manual transmission instead of dedicated transmission oil? My honda's manual allows motor oil as a temporary measure although insist on changing it with MTF ASAP. What are the cons when it comes to motor oil in manual transmission?

 

[aquariuscsm]

I'd guess motor oil doesn't have the necessary additives for ultimate synchro engagement.

 

[antonmnster]

My Saab 900s used 10-30. Shift quality improved when I switched them to synthetic 10-30.

Does this thread go in the trans oil forum since we're talking about transmissions, or does it stay here since we're talking about motor oil in transmissions?

 

[The_Jeff]

The NV1500 in my 91 dakota called for 10w30. I ran syn.

 

[Panos]

You should seek why an engine oil would be better than a gearbox oil, not the opposite. Well, usually a gearbox oil is a very shear stable fully synthetic oil which is not formulated to withstand blowby ,seal conditioning etc. So they must be different things and you should prefer the gearbox oil IMO

 

[MolaKule]

Originally Posted by antonmnster
My Saab 900s used 10-30. Shift quality improved when I switched them to synthetic 10-30.

Does this thread go in the trans oil forum since we're talking about transmissions, or does it stay here since we're talking about motor oil in transmissions?

Yep, it should go in the forum linked below as the topic has been discussed before there:

https://bobistheoilguy.com/forums/ubbthreads.php/forums/16/1/atf-differential-trans-brakes-p-s

 

[Mainia]

IF you are going to try it run Redline oil

 

[JAG]

The negative is that the additive package is not optimized for gear lubrication. I'm sure there are better papers on gear tribology, but this one is a good start. http://www.diva-portal.org/smash/get/diva2:556276/fulltext01.pdf

 

[CR94]

Honda used to specify engine oil for their manual transmissions, with no other option listed. When did that change?

 

[Revving2Redline]

It was conventional 10w30 in our CRX. Syn 10w30 is too slick! Use Honda MTF, Pennzoil Synchromesh or Redline MTL.

 

[charbaby]

At one time(during the 80s) when I was first buying Honda's, their manual transmission required 10W30 motor oil. I believe they required the 10W30 some time into the 90s. But, the motor oil was different back then. This was during the SE/SF/SG/SH time frame.

 

[MolaKule]

Originally Posted by Mainia
IF you are going to try it run Redline oil


Redline has to much MoDTC which interferes with synchro lockup.

 

[Bailes1992]

I believe some of the Honda related Rovers and MG's requested 10w40 engine oil or MTF94 in the late 80's and well into the 90's.

Today, I'd use a quality 75w80 GL-4 oil.

 

[benjy]

many fluids used in cars + trucks are basically petroleum products, either refined or synthesised in a lab. every application requires different additives as well as certain viscosities, so run what is made for the application!! of course an emergency is different, but the wrong emergency fluid could be costly $$$$

 

[parshisa]

Interesting. Not that i had an intention to run something different other than MTF but was curious to if anyone tried that. Thanks for y'alls replies folks

 

[92saturnsl2]

The Borg Warner T19 4-speed in my F-250 takes either 80w-90 GL4 gear oil, or SAE 50 motor oil.

When I bought the truck, the PO had used GL5 gear oil, which I wanted to switch out as it has a reputation for being rough on non-ferrous metals inside manual transmissions. I had trouble finding an 80w90 lube that was GL4 without spending $10+ a quart on OEM manual transmission fluid (or Amsoil), so I used SAE 50 motor oil.

Product was Valvoline VR1 racing SAE50 (on sale for $3 a quart), the shift quality is actually a bit better than the GL5 80w-90 that it replaced. Still shifts very firm when extremely cold (0F or below) but the gear oil was worse in that regard.

 

[Chris142]

Originally Posted by 92saturnsl2
The Borg Warner T19 4-speed in my F-250 takes either 80w-90 GL4 gear oil, or SAE 50 motor oil.

When I bought the truck, the PO had used GL5 gear oil, which I wanted to switch out as it has a reputation for being rough on non-ferrous metals inside manual transmissions. I had trouble finding an 80w90 lube that was GL4 without spending $10+ a quart on OEM manual transmission fluid (or Amsoil), so I used SAE 50 motor oil.

Product was Valvoline VR1 racing SAE50 (on sale for $3 a quart), the shift quality is actually a bit better than the GL5 80w-90 that it replaced. Still shifts very firm when extremely cold (0F or below) but the gear oil was worse in that regard.

20w50 in mine!

 

[oliver88]

Many older English cars specified non-detergent 30 weight or 20w50 oil for the gearbox. I have used both of those and Redline MT 90....Redline was far superior for shifting and noise reduction in my 1962 Austin Healey 3000.

 

[Silk]

Originally Posted by CR94
Honda used to specify engine oil for their manual transmissions, with no other option listed. When did that change?


Yes that was the case for many years...I suspect that engine oil is still OK, but they made their own oil spec and want you to use that instead. Seperate gearbox motorcycles (2 strokes) always spec engine oil too.

 

[Hounds]

Originally Posted by parshisa
Interesting. Not that i had an intention to run something different other than MTF but was curious to if anyone tried that. Thanks for y'alls replies folks

I did.

First, I'm going to guess you have an early '90s Honda. The owner's manual language you referred to in your first post was actually a change from what Honda recommended in the '70s and '80s when 10w30 weight conventional motor oil was the recommended fill. Like you perhaps, when I read the language in the 1990 owner's manual, out of curiosity I decided to experiment with Mobil 1 5w30 in a '90 Civic Si. It worked well enough initially that I opted to leave it in the transmission for nearly 20k miles, when I decided to experiment further with a mixture of Honda's (early semi-synthetic) MTF and Amsoil's fully synthetic MTF. The latter, I believe, is an excellent choice for any Honda manual transmission. I now have it in a Honda 6-speed MT, a '15 Accord Sport. I recommend it to anyone who is complaining about Honda's infamous 2nd gear crunch. The coefficient of friction is roughly 20% higher than Honda's current (synthetic) MTF, and I believe that's why it performs better than Honda's MTF from initial start-up (particularly in cold weather) and thereafter.