10W30 or 5W30 as Manual Trans Fluid!
 

I was just at the parts counter of a local Honda dealer and I was trying to figure out how many bottles of MT fluid I need for my mechanic that is doing a clutch job. I knew I had about 1/2 a litre (quart) lying around and I remember that a MT drain and refill is about 1 and 1/2 bottles of fluid. So I asked: "if my mechanic is a few ounces short, can he top it off with some other brand MT fluid"?

The mechanic answered: "just have him top it off with 10w30 or 5w30. No problem. When some customers complain about difficulty shifting in winter, sometimes we do half MT fluid half 10w30"! I was surprised. He made it seem like motor oil might actually help make shifting smoother, especially in winter.

The mechanic in question is supposed to be the guy that works on all the transmissions at the dealership and apparently knows what he's talking about. I was really surprised, especially considering the phrasing in the owner's manual really makes it seem like 10W30 should be only a last resort.

Can you do it? Yes.

Should you do it? No.

Motor oil doesn't have the shear additives that MTF has. Like is posted in the manual, it's a last resort. The viscosity is similar, so it technically "works" but not well in the long run.

This is the same line of thinking that says you should be changing your oil every 3k miles and running 15w50 in high mileage motors. Old group-think. leave it alone.

Ok... So what if I go check my leftover bottle at home and I only have 0.4 litres in it totalling in 1.4 litres. Service Manual calls for 1.6 litres for transmission overhaul so is .2 litres of 10W30 a big deal? Is it worth buying a full bottle of transmission fluid to be safe?

I would just go buy the extra bottle.

It is only a couple bucks.

Okie dokie. Hi Mike, how's the Fiesta?

What he said. :thumbups:

With oil, it is never only about oil. It's also about additives.

10w-40 if you must use oil. But dont use some fancy anti-sludge crap. use generic brand regular 10w-40. as little "cleaner" additives as possible.


synchromesh is a way better alternative to motor oil though. I used to run one quart or so, then top with honda MTF before they changed their formula and basically stopped providing fluid for the older hondas

Just seems wasteful. I have exactly 1.45 litres of MTF. Since my mechanic is dropping the tranny for a clutch job I suppose it could count as an "overhaul" so it would require 1.6L (as per the service manual). So that's a whole other bottle for 150ml of fluid.

That's the thing. You should never "waste" money on your car. It's much better to spend hundreds of dollars to drop the tranny and do a clutch, then, at the last second, cheap out and save $8 on a quart of MT fluid. That makes sense to me. :D

It's the same thinking as buying a used car at a "great" price with 4 million miles on it, so you can spend every second of owning it on complaining about what doesn't work and "fixing" the problems in your usual half-a**ed way. It's as American as apple pie, I say. :D :D

Nothing special. MPG are good, that's really all I care about haha. I knew the car wouldn't be fun/pleasant to drive going in, that's what my future project car is for.

You guys are too critical.

Back in my early Honda days, I remember that Honda SPECIFIED 10W-30 motor oil for the manual transmissions.

:bowdown:


Granted, today's MTF is a special blend of oil and gear additives, but I've found myself a few ounces short due to my own klutzy spillage , so have topped it up with the synthetic motor oil I am currently using, with no ill effects. (I think the proper oil level is more important than type.) :ohnoes:


That said, since MTLian KNOWS he is short a bit, purchasing that extra bottle of MTF is what he should do.

I'll follow the advice here and get the bottle. But I'm still surprised that the mechanic, who is a specialist in transmissions at the dealership uses a 50/50 blen of motor oil and MTF to cure transmissions that are hard to shift in winter.

I asked him: "what about GM synchromesh?" And he told me that Hondas don't have the same type of synchros as GM and they don't use the special synchromesh fluid...

GM Synchromesh has been used by enthusiasts in Hondas with worn synchros since Synchromesh was released lol it's pretty standard and common practice and it helps some apparently.

I don't bang gears so IDK, I never have synchro problems :D

True. This is a much-beloved product among forum-istas. Not sure if there is a caveat regrading exactly which "GM Synchromesh" to buy. I seem to recall that they have a few that are similarly named.

Note: Probably no fluid will help worn or damaged synchos. But a good fluid will improve function of good synchos.

The one i've heard about is called friction modified. It isn't cheap either. I'll probably just stick with Honda MTF. Still bummed that my input shaft bearing went bad or else my clutch was still plenty good... So much work for a stupid bearing.

I saw this posting on BobIsTheOilGuy regards the characteristics of manual trans fluids today, kinda interesting. Don't be put off by the title...

:bowdown:



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