Dexron ATF in my Yanmar Trans Gear?

[AmicaJim]

Sailboy, I have added a qt. of ATF to my oil a week prior to changing it and it does clean things up. got 260K+ miles on it and will be rebuilding this month (just a leaky rear main seal).

[NOLAsailing]

Yes - there are some applications that allow ATF or motor oil to be used. I don't know if this applies to marine transmissions, but it could! Check your facts before you berate others.

It could or it does? I need to check my facts?

This is precisely the type of answer that gets to me. When it comes to technical questions, supposition can cause a lot of harm.

[AmicaJim]

Originally Posted by NOLAsailing

I can't believe that I've just read a thread where a consensus seems to be forming that you can substitute SAE 30 motor oil for automatic transmission fluid.

Sounds like a statement that you can't substitute ATF for oil to me. One contradiction makes the statement false. You didn't specify only marine transmissions. My suggestion for all is to RTFM (read the fine manual ).

Just my .02

[NOLAsailing]

The "fine" manual will specify ATF or motor oil.

As this is a sailing forum, I'll go ahead and take the liberty now of specifying marine transmissions, in case anyone is a little confused.

So - for marine transmissions, unless you are absolutely certain that you can do so or do do not care about your transmission - you cannot substitue motor oil for ATF or vice verse. Regardless of what anecdotal evidence you find carelessly sprinkled about the internets.

I hope that helps.

[c40eb]

Hmmm...I have a Westerbeke 20B Two with JS tranny. The engine manual states it should have SAE 30 oil. When we bought the boat and I first checked the transmission fluid level, it was...pink. Hmmmm...

Well, it's been changed and I am using SAE 30.

[Faster]

FWIW, Hurth transmissions DO specify ATF.

[JohnRPollard]

Jason,

I have both the Yanmar Operation Manual and the Service Manual for your engine right here. They clearly state that the transmission coupled with the 2GM20F should use the same weight Motor Oil as the engine. Not until you bump up several sizes to the 3HM35F do these manuals call for ATF.

HOWEVER, if you want to know without a doubt, Kanzaki stamps the required fluid into the backside of the transmission housing, just above the output shaft.

In my case, with a 3GM30F and a KM3P transmission, the service manual states to use whichever weight motor oil is being used in the engine. But the stamp on the transmission housing indicates 20W/30. I suspect you will find the same info on your KM2P.

[jason3317]

John, thanks for bringing this back on topic. I will have to check the plate on the trans, just for S&Gs.

Let me add a few clarifying points for the group.

1. I do have and have read both the Yanmar owner's manual and service manuals for my 2GM20F / KM2P combo. Engine and manuals are circa 1988. Each specifies SAE 30 or similar multigrade motor oil to be used in both engine and the gear.

2. I do believe that there is a real difference between SAE 30 motor oil and ATF.

3. I would have used motor oil in the trans if in fact I had done the replacement myself. ATF wasn't even on the radar.

4. I clearly specified on my haulout order the brand / weights of lube to be used in the engine and gear - in fact, I even provided the oil and filter. However, the yard disregarded my instructions and justified by stating they called Yanmar on my specific situation and YANMAR specified ATF. My guess is they didn't correctly identify the gear model if/when they called Yanmar last week.

Now...we all know that the probability of a Yard Error is pretty high. Bottom line....I think the yard owes me a drain + flush + refill of the tranny.

That said, I was curious if it is possible that Yanmar has revised their specs to allow ATF in the KM2P gear?

[sailingdog]

Jason—

Given they screwed it up the first time, do you really want them to do the work a second time... I'd rather have them pay someone else to do the drain, flush, and refill...

Originally Posted by jason3317

John, thanks for bringing this back on topic. I will have to check the plate on the trans, just for S&Gs.

Let me add a few clarifying points for the group.

1. I do have and have read both the Yanmar owner's manual and service manuals for my 2GM20F / KM2P combo. Engine and manuals are circa 1988. Each specifies SAE 30 or similar multigrade motor oil to be used in both engine and the gear.

2. I do believe that there is a real difference between SAE 30 motor oil and ATF.

3. I would have used motor oil in the trans if in fact I had done the replacement myself. ATF wasn't even on the radar.

4. I clearly specified on my haulout order the brand / weights of lube to be used in the engine and gear - in fact, I even provided the oil and filter. However, the yard disregarded my instructions and justified by stating they called Yanmar on my specific situation and YANMAR specified ATF. My guess is they didn't correctly identify the gear model if/when they called Yanmar last week.

Now...we all know that the probability of a Yard Error is pretty high. Bottom line....I think the yard owes me a drain + flush + refill of the tranny.

That said, I was curious if it is possible that Yanmar has revised their specs to allow ATF in the KM2P gear?

[jason3317]

Originally Posted by sailingdog

Jason—

Given they screwed it up the first time, do you really want them to do the work a second time... I'd rather have them pay someone else to do the drain, flush, and refill...

No, I'd rather them redo their work correctly and to my satisfaction, even if they do 10x. It's just an oil change and I don't believe this mistake was intentional, just unprofessional and shortsighted on their part.

As I like to say: "Trust, but Verify".

JS