How do you properly change your transmission fluid?

Synchros shot? Weird noises while shifting? Not sure what needs to be replaced?
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Re: How do you properly change your transmission fluid?

Postby bk7794 » Mon Aug 06, 2012 7:22 pm

theholycow wrote:
bk7794 wrote:So I was doing more research on this topic. Apparently gear oil viscosity is much much different then normal motor oil.

http://en.wikipedia.org/wiki/Gear_oil
API viscosity ratings for gear oils are not directly comparable with those for motor oil, and they are thinner than the figures suggest. For example, many modern gearboxes use a 75W90 gear oil, which is actually of equivalent viscosity to a 10W40 motor oil.

Still a bit worried about changing the fluid.

Don't worry. Unless you drain or fill the wrong thing (a friend's brother drained the transmission and filled the engine) or forget to put the drain plug back in (a mechanic forgot to put the plug back in my mom's engine), the worst case scenario is that you spill the oil instead of catching it neatly.

EDIT: Crap its actually 10w-30/40 listed for all year around. So what do I get? It also says 20w-40 or something for anything over 0 degrees.

We get close to (and below) 0°F enough that you should go with the all-weather recommendation rather than the "anything over 0" one.

I think I still will stick to the 10w, just to be safe.

Yeah I hear of jiffy lube doing that, scary thought if you think of it. Whatelse must just regular mechanics forget.

Well thats the thing, it has 10W30 on one side of the arrows, and 10w40 on the other side of the arrows. I might just do 10w-30. I will just get synthetic, that should be okay right. Even if there was conventional in there beforehand?
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Re: How do you properly change your transmission fluid?

Postby theholycow » Mon Aug 06, 2012 7:42 pm

It's nearly unavoidable, IMO, for a professional to make that sort of mistake once or twice in his career of doing that job a zillion times. To err is human, and professionals tend to be in a big hurry (especially doing a low-margin oil change). They have insurance for that sort of thing but it's tough to quantify potential damage that is not evident when you only drove down the street a little before realizing that they screwed up.

I think whichever oil you choose will be fine. 10W30 synthetic sounds like a decent enough plan. Switching to premium synthetic on a 300,000 mile engine that's always had the cheapest dinosaur juice might be a concern, if there's a big difference in detergent levels. A manual transmission is much more simple than an engine. It's one box with some basic crap in it, no circulatory system, nothing particularly sensitive (except I've heard that some special additives for limited slip differentials or something can attack brass synchronizers).

Seriously. This is 100% of the guts of mine:
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Re: How do you properly change your transmission fluid?

Postby bk7794 » Mon Aug 06, 2012 7:58 pm

theholycow wrote:It's nearly unavoidable, IMO, for a professional to make that sort of mistake once or twice in his career of doing that job a zillion times. To err is human, and professionals tend to be in a big hurry (especially doing a low-margin oil change). They have insurance for that sort of thing but it's tough to quantify potential damage that is not evident when you only drove down the street a little before realizing that they screwed up.

I think whichever oil you choose will be fine. 10W30 synthetic sounds like a decent enough plan. Switching to premium synthetic on a 300,000 mile engine that's always had the cheapest dinosaur juice might be a concern, if there's a big difference in detergent levels. A manual transmission is much more simple than an engine. It's one box with some basic crap in it, no circulatory system, nothing particularly sensitive (except I've heard that some special additives for limited slip differentials or something can attack brass synchronizers).

Seriously. This is 100% of the guts of mine:
Image

Looks so awesome! But do you think the extra detergents will eat my synchronizers? Or the gasket between the two halves of the transmission?

I was considering mobil 1.

Also will my syncros work properly because of the friction fighters?
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Re: How do you properly change your transmission fluid?

Postby theholycow » Mon Aug 06, 2012 8:50 pm

I think the only way you'll feel 100% comfortable is by using exactly what the manual recommends, no more, no less, and searching Civic forums to see if people have had good luck with exactly the product you choose. You're worried about using synthetic, so why bother using it? You don't need that worry, and realistically you don't need the advantages that synthetic is supposed to bring to the table. Your car successfully made it to 300,000 miles on dinosaur juice, obviously the stuff does the job.

Addressing your specific questions:

Synchronizers -- I seriously doubt anything in any engine oil will hurt them. I'm sure anything that synchronizers can be made from is also found in some engines.

Gaskets -- There's no question that transmission gaskets are made from materials that are used in engine gaskets too.

Friction/synchros -- Synthetic isn't magic and it's not majorly different from dinosaur juice. It's a direct drop-in replacement. It's supposed to do the same stuff that dinosaur juice does, just with fewer impurities and lasting longer. It's just not that different. They have the same additives and these days most synthetics are made from dinosaur juice anyway, just refined a little more thoroughly.
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Re: How do you properly change your transmission fluid?

Postby bk7794 » Mon Aug 06, 2012 9:40 pm

theholycow wrote:I think the only way you'll feel 100% comfortable is by using exactly what the manual recommends, no more, no less, and searching Civic forums to see if people have had good luck with exactly the product you choose. You're worried about using synthetic, so why bother using it? You don't need that worry, and realistically you don't need the advantages that synthetic is supposed to bring to the table. Your car successfully made it to 300,000 miles on dinosaur juice, obviously the stuff does the job.

Addressing your specific questions:

Synchronizers -- I seriously doubt anything in any engine oil will hurt them. I'm sure anything that synchronizers can be made from is also found in some engines.

Gaskets -- There's no question that transmission gaskets are made from materials that are used in engine gaskets too.

Friction/synchros -- Synthetic isn't magic and it's not majorly different from dinosaur juice. It's a direct drop-in replacement. It's supposed to do the same stuff that dinosaur juice does, just with fewer impurities and lasting longer. It's just not that different. They have the same additives and these days most synthetics are made from dinosaur juice anyway, just refined a little more thoroughly.

This makes so much sense, and gets rid of a lot of my stupid worries. I want to use synthetic specifically for the winter and extended drains. Then again..once I do it I will feel more comfortable.

In the winter I can tell that there is a load on the engine when I drop the clutch in neutral to warm the oil up. I can also tell 2nd gear sucks to get into gear when its cold. Hopefully this will rid some of the problems.

Now the viscosity, go with 1040 or 1030.
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Re: How do you properly change your transmission fluid?

Postby theholycow » Mon Aug 06, 2012 9:58 pm

bk7794 wrote:Now the viscosity, go with 1040 or 1030.

Here's your answer:
specifically for the winter

In the winter I can tell that there is a load on the engine when I drop the clutch in neutral to warm the oil up. I can also tell 2nd gear sucks to get into gear when its cold.
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Re: How do you properly change your transmission fluid?

Postby bk7794 » Mon Aug 06, 2012 10:00 pm

theholycow wrote:
bk7794 wrote:Now the viscosity, go with 1040 or 1030.

Here's your answer:
specifically for the winter

In the winter I can tell that there is a load on the engine when I drop the clutch in neutral to warm the oil up. I can also tell 2nd gear sucks to get into gear when its cold.

So the thinner one. 1030. Though I thought I read on BITOG that its basically the same when cold. Its just that when hot the 40 is a bit thicker
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Re: How do you properly change your transmission fluid?

Postby theholycow » Mon Aug 06, 2012 10:16 pm

bk7794 wrote:So the thinner one. 1030. Though I thought I read on BITOG that its basically the same when cold. Its just that when hot the 40 is a bit thicker

Yes, the 10 represents its viscosity rating when it's cold, and the other number (30 or 40) represents its viscosity rating once it is thoroughly warmed up.

If it's too heavy when cold you could try a 5W30 or 5W40.

Maybe you should go with dinosaur juice and change it a few times until you decide on the viscosity rating you like best.
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Re: How do you properly change your transmission fluid?

Postby bk7794 » Tue Aug 07, 2012 5:03 pm

theholycow wrote:
bk7794 wrote:So the thinner one. 1030. Though I thought I read on BITOG that its basically the same when cold. Its just that when hot the 40 is a bit thicker

Yes, the 10 represents its viscosity rating when it's cold, and the other number (30 or 40) represents its viscosity rating once it is thoroughly warmed up.

If it's too heavy when cold you could try a 5W30 or 5W40.

Maybe you should go with dinosaur juice and change it a few times until you decide on the viscosity rating you like best.


That is a good idea! How would I know if its too thin when warmed up? It will scrape right?
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Re: How do you properly change your transmission fluid?

Postby theholycow » Tue Aug 07, 2012 7:44 pm

bk7794 wrote:That is a good idea! How would I know if its too thin when warmed up? It will scrape right?

I'm guessing it won't be and you won't be able to tell the difference. If it is and you can tell, it will probably be either difficult to get into gear or you will grind gears (really, clash synchros) too easily. Those are guesses, though, I definitely have neither the experience nor the study to say.

Anybody else have something more worthy to say?
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Re: How do you properly change your transmission fluid?

Postby Rope-Pusher » Fri Aug 10, 2012 6:49 pm

But wait, it gets better....vehicles are now being designed with active grill shutters and belly-pans for aerodogdamnics. The transmissions, engines and axles run warmer, so there is less viscous drag and the shift qualities, hydraulic valve actuation, and a load of other design considerations are all taken into account at these higher average temperatures. Now if your active grill shutters get stuck in the open position, or if your belly-pan gets ript off by a snow drift, your shift quality goes to Aichey-Double-Hockeystix, you pick up a neutral rattle, your engine starts idling rough or making strange noises,....it's the end of the world as we know it! When designs are drawn with a finer point, little changes start to matter. You may be better off not changing anything and running the fluids the owner's manual calls for.
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Re: How do you properly change your transmission fluid?

Postby theholycow » Fri Aug 10, 2012 6:59 pm

Hooray! Rope-Pusher's here!

Would a 1991 Civic with 300,000 miles fall under the category of fine-point design? It should be a pretty basic, old-tech machine.
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Re: How do you properly change your transmission fluid?

Postby watkins » Fri Aug 10, 2012 10:44 pm

Active grill shutters on the 2013 Ram are going to be pretty cool, so long as Chrysler doesn't find a way to f*ck those up too...
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Re: How do you properly change your transmission fluid?

Postby Shadow » Mon Oct 15, 2012 11:01 pm

bk7794 wrote:So I was doing more research on this topic. Apparently gear oil viscosity is much much different then normal motor oil. Again I will double check to see the motor oil equivalent is but I was looking at getting this. http://www.redlineoil.com/product.aspx?pid=45&pcid=7 Redline MTL 70w-80.

The reason for changing the fluid is because I am getting notchy shifts, even at stand still.


I just put Redline MTL 70W-80 GL4 in my Audi. Now that it's starting to get cold out again, I'm starting to notice a slightly notchy 2nd gear shift when the gear oil is cold. The Redline MTL is supposed to eliminate notchy shifts due to cold temps. BTW, the stuff is expensive. I paid $75 for 5 quarts.
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Re: How do you properly change your transmission fluid?

Postby potownrob » Mon Oct 15, 2012 11:59 pm

Shadow wrote:
bk7794 wrote:I just put Redline MTL 70W-80 GL4 in my Audi. Now that it's starting to get cold out again, I'm starting to notice a slightly notchy 2nd gear shift when the gear oil is cold. The Redline MTL is supposed to eliminate notchy shifts due to cold temps. BTW, the stuff is expensive. I paid $75 for 5 quarts.
could it be that that oil is a little thin for that tranny?? i thought 75-90 was the OEM fill. if it's anything like subaru trannies, you can get away with having mostly lower viscosity oil and then one heavier oil (they call the mixture a cocktail in the subaru community).
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