ATF and engine braking

[n00b76]

I own a 2001 mitsubishi galant and i'm going to change the ATF this weekend. As i read on the web heat is a transmissions worst enemy. And i love engine braking with the transmision (the engine makes a cool noise,lol). I understand that engine braking overheats the transmission. So im looking for fluid that takes good care of the heat.

Here's my current options:
-valvoline dex/merc
-castrol multi import atf

looks like a synthetic oil like royal purple would be a better option but i can't afford royal purple or any other synthetic at this time.

 

[LeakySeals]

Check out the Lubegard Website. An additive for heat blessed by transmission re-builders and new car manufacturers. I linked you to Lubegard Red but there are other options. Check the chart for a match.

Using a bottle of this in the cheap stuff may make it better than the expensive stuff.

 

[n00b76]

wow that lubegard looks like exactly what i need...Is it compatible with my tranmision?

my owners manual asks for "Diamond SP-II"

 

[LeakySeals]

I see it on the chart. Page 34

http://www.lubegard.com/pdfs/2010_LUBEGARD_CC_FINAL.pdf

 

[n00b76]

ok thanks for your help...Looks like im going for the lubegard platinum,since im not going to use the oem fluid anymore.

thanks alot.

 

[Rand]

is platinum the converter fluid?

you want regular lubegard if you are using a recommended fluid.

I think you use the converter fluid with dex/merc

 

[kschachn]

I have used M1 ATF for the life of my Sienna and most of the life of the Accord (and now in the BMW). They no longer list a host of compatibilities, but if you are looking for a Dex III fluid I can give it my total approval. When I drop the pan on the car it is very clean inside with a minimum of gray clutch material and almost no metal on the magnets.

And oops, sorry I didn't see your disclaimer about cost. Yeah, this isn't cheap. But you can get Autozone to drop the price a bit if you ask about buying a whole case.

 

[Donald]

Are you manually downshifting the transmission to do braking? If you are price the cost of a rebuilt transmission vs brake pads and make the decision.

A synthetic like Amsoil is cheaper than other ATFs is you figure it can go 50K severe and 100K normal. Few others can go that distance. As always a Magnefine inline filter for $20 would be a big plus with any ATF.

 

[JimPghPA]

If you are planing on keeping it for several more years, you should consider a trany cooler. It is a heat exchanger like a small radiator, the better ones have a thermostat that bypasses the cooler when the fluid is cold. All trany coolers should be installed so the flow of fluid is first through the add on cooler, and then through the existing heat exchanger built into the radiator. This is so the hot antifreeze heats up the trany fluid on cold days.

 

[BearZDefect]

Originally Posted By: JimPghPA
... All trany coolers should be installed so the flow of fluid is first through the add on cooler, and then through the existing heat exchanger built into the radiator. This is so the hot antifreeze heats up the trany fluid on cold days.

I disagree with this assumption.

At least on my car, the engine coolant circuit to the radiator has a thermostat while the ATF cooling circuit does not.

So on cold winter days, the engine coolant thermostat stays closed for a long time as the engine warms up. Meanwhile the ATF is flowing through the radiator full of freezing cold coolant - the transmission heat by itself is no match for the freezing cold air blowing between the radiator fins.

I think the ATF cooling through the radiator causes the transmission to take much longer to warm up. Even though the engine may be close to operating temperature, the radiator may still be very cold.

 

[mechtech2]

All aftermarket coolers go through the stock radiator cooler, THEN the aftermarket cooler.
This has a few advantages, like better warm up and better consistency, along with better cooling.

Since no mfr goes through the new cooler first, and there is no logical reason to do so otherwise, why would anyone recommend this way??

 

[BearZDefect]

I was thinking that if the aftermarket cooler has a cold fluid bypass that the in-radiator cooler could be left out of the circuit.

Why? Simply because, in my opinion of limited experience, the engine radiator in the ATF cooling circuit has two undesirable characteristics:

1. It keeps the ATF cold longer in the winter, well below optimal operating temperature, unless the OEM ATF cooling circuit has its own thermostat.

2. It keeps the ATF hotter in hot weather because the engine is dumping a lot of heat into the radiator.


My points have two assumptions: First that the aftermarket cooler has sufficient capacity to cool the transmission on its own, even with no headwind. Second that the aftermarket cooler has a mechanism to bypass the cooling when the ATF is cold.