Trans fluid whats best??

My local parts shop has regular 20w oil and I'm wondering if which is best for my trans, 20w or ATF. Everyone seams to going ATF because no one seams to stock 20w anymore, but given a choice, what would yall run?

Thanks!!
Sammy

The ATF's high detergents keep the internals clean. It's primarily to keep varnish from building up on metal parts like clutch plates.

From CC several years ago:

Hi Sean

Thank you for bringing your question to us. The simple answer is Dexron III
is what PCM currently recommends. PCM first used 20W oil (commonly found in
motor cycles and farm equipment) and this likely is what came in your
transmission when new (when your owners manual was printed).

While Dexron has a 20W viscosity, it cannot be mixed with oil.
To switch from 20W oil to Dexron, drain and fill your transmission with
Dexron, run the engine until warm, then immediately drain and fill again.

Please feel free to call or write back if you have further questions.

Regards,

Jim Jetmore
Customer Service
Correct Craft, Inc.
------------------------------------------------------------------------

   Customer Service,

>
>      I own a 1992 Ski Nautique with the PCM PRO BOSS engine and PCM-40A
>      1.23/1 transmission. The plate on the transmission and the boat
>      owners manual both specify to use 20 - 20W engine oil in the
>      transmission. Because I couldn't find 20-20W engine oil I spoke to a
>      Nautique dealer and another marina that services Nautiques and they
>      both said to use Dextron III ATF. What oil should I be using ?
>
>      Thank You,

Is there a way to tell whats in the transmission (oil or ATF). I want to change my transmission fluid in the spring and don't know what the previous owner put in.

I have a 1985 ski nautique. The boat had been in storage for 13 years until last summer when I got it running and starting taking it out. I figured a transmission service is necessary. it calls for type a fluid according to the sticker on the valve cover (looks like and engine oil color). Seems from this thread that I will be changing to dexron III?? I own a vacuum evacuator I am wondering if it would be best to put it in the lake and pull out what i can and fill with the dexron and do that a few times until it looks like the dexron? Or is it worth trying to drain and fill a couple times??

Gary S wrote: ATF Sammy . There was a reason PCM changed from 20w to ATF but I cannot remember

Here's the story in case anyone is still interested. In 1989 when PCM came out with the 40 Series transmissions, the 40A, otherwise known as the 1.23:1, had a whine in the reduction gears. We at CC complained bitterly to PCM, as did our customers to us. PCM decided to change the recommended oil to 20 weight motor oil. Then we found out that not only did it not help any on the whine issue, but also that it is very difficult to find in the southern states. (I know.... that wouldn't be the case nowadays with many new automobiles using it. I cringe whenever they put it in my truck, but that's what the dealer says it has to have)
Anyway, back to the PCM story. They made stick-on labels to put on the transmission ID plates saying to use 20W. When the above was discovered, they went back to ATF. Some of those old stick-on labels are still around. Truthfully, the transmissions don't care which you put in them, or you can mix them if you want. The friction factor in the clutches might be slightly reduced with the motor oil, but there has been no discernable reduction in life or performance when it was used.
The now-current 80 series transmissions are far better units than the 40 series, and they are Made in the USA!

The internals of them look a whole lot like a Velvet Drive / Warner Gear, and many of the parts appear to be common with the AS1 71 series later known as the 1017. The 80s are in an aluminum case, making them a bit lighter than the 40 series equivalents. They are completely retro-fittable, same dimensions all over as the corresponding 40s. .

Warner sold their marine division many years ago, and it was picked up by a couple of different owners after that. Currently it is known as Velvet Drive division of Richmond Gear and they are located in Liberty, SC, which is located probably not coincidentally close to Little Mountain, where PCM resides. I strongly suspect that they are building the 80 series gears that are branded as PCMs.

Yes, the 40s are definitely aluminum cased, and many internal parts are aluminum also. The 80s have a lot more iron parts inside. A 40A (1.23:1) is 68 lbs.. and the 80 version is 92. A 1017 is right at 100.

The 40 is a ZF design, it was made in italy also.
Eric has always noted the 40's as a "wallmart transmission", not so good for high torque apps, I think one of the reasons for a tougher transmission are the G-series boats and the newer more powerful engines for heavy loaded wakeboard/wakesurf boats. They had some transmission issues with the earlier boats as well.

Are the PCM 1:1s the same as the Hurths that Indmar used? They were made by ZF in Italy as well.   We haven't had any problems with ours, but it does not shift as smoothly and is no where near as quiet as a Velvet Drive.

Riley wrote: Are the PCM 1:1s the same as the Hurths that Indmar used? They were made by ZF in Italy as well.   We haven't had any problems with ours, but it does not shift as smoothly and is no where near as quiet as a Velvet Drive.

I don't think the transmissions are interchangeable. To the best of my knowledge, the 40I 1 to 1 was a proprietary unit only sold through PCM. I'm not familiar with a Hurth that's identical.

Just top clear up the terminology a bit, the 40 i (as in like the letter "I" stands for "inline,." as in the input and output shafts are in line with each other. The 40A, which we call the 1.23 to 1, is an "Angle" unit' the input and output shafts are at 5 degrees to each other. (or is it 9 degrees? My brain is still in neutral!

Dex/merc

Wait ..... so either, or are you guys disagreeing on which is best?

Just bought one of these at Wally World

or use Dexron VI it's backwards compatible

Why non synthetic? In ATF? Lay some learning on me.