Hi all. As the title says I accidentally premixed with ATF oil. I was really tired and in a hurry, my garage was really dark and I poured the ATF oil in my fuel tank.


I poured 100ml (3.3oz) to a half tank of gas.


I know that some people are using this trick for serious flooding situations, and sometimes as a general maintenance item but I also read in Aaron's website (https://www.aaroncake.net/rx-7/atftrick.htm) that it is really bad for our engines. My engine block is almost new (recent rebuild), it has only 30K miles and I don't wanna harm it in any way.


Any advice? Should I add more fuel in the tank in order to dilute the oil some more? Is it ok to leave it like that and continue to drive the car? Should I flush the tank?

 

I forgot to mention that the car is S5 turbo and the ATF oil was really old, I had that bottle for more than 10 years.

 

There's a drain plug on the bottom of the tank, I'd drain it. Then maybe put the plug back in, pour in a gallon or so and bounce the rearend around to swish the gas around and drain it again.

 

I would just fill the tank up and premix with the correct oil and maybe add an extra ounce or two.
3 oz isnt very much and being that diluted I cant see it making any deposits in the engine.

 

I would err on the side of caution and drain what's in there using the aforementioned drain bolt. Then fill it up all the way, premix with your usual ratio, and don't worry about it.

 

Thanks guys for all your replies. I talked to another rx owner and said that it will probably not cause any trouble because the quantity was not that much. But I am thinking to just drain the tank. Any other advises are always welcome.

 

I keep reading posts about the ATF trick or treatment and the opinions are divided. Many notable users like Rotary Resurrection and others claim that it is not causing any trouble.

https://www.rx7club.com/2nd-generati...-seals-437687/

I am still confused and curious about this subject so if anyone has any experience with ATF, please share it. Thanks.

 

For years, owners/dealerships used ATF to get engines running without any problems. The '88 TII we purchased new wouldn't start after sitting in
the garage the first year over the winter, 4,000 miles, so off to the dealership. At that time they had numerous cars not able to start after sitting,
used ATF and no problems that I'm aware of.

 

Yes, old school mechanics used this trick all the time. I also watched many vids in youtube that show how to use premixed ATF in diesel engines. But I wonder why nobody experimented with ATF as a premix in rotaries.

 

So you had 3oz of ATF in about a 1/2 tank of fuel? Should not be an issue, but just to be safe what I would do is fill the tank with gas and drive the car normally. If you're not running the stock OMP, I'd add the correct amount of proper TCW3 rated pre-mix lube to the tank when you fill up, but otherwise I'd skip the premix for the next few fill-ups. Then top off the tank again when it hits at 3/4 tank, rinse & repeat once or twice more. Each time you do that, you're further diluting that 3oz of ATF to the point of it being completely negligible.

 

i would just fill the tank up and keep driving.

1 gallon = 128oz. lets say half tank is 7 gallons, 896 oz. 896/3.5 = 0.003%

 

Yes the quantity of the ATF oil that I poured is not that much and the procedure that you describe is what I thought to do. I have deleted the OMP so I have been premixing since then. I will fill the tank and add some Idemitsu premix oil that I bought. Thank you guys for all the advices. You opinions are valuable.

 

That was my first thought after the "accident" . I just wanted to be sure because the engine works great right now.
Thanks.

 

because it has an excess of un-needed additives for the transmissions it goes in, and two stroke oil was already practically perfect for rotary engines.

 

That's true, but I thought that maybe someone has used it in premix since some people claim that it can lubricate better and remove carbon deposits at the same time. But it seems that the carbon removal properties of ATF are overrated. Even in diesel engines the "after" effects are not that obvious.

 

You'll be fine. Do plug exam once this tank is dry and you've run a few more gallons through.

 

I will definitely do that. Thanks

 

Just to add to the discussion above about ATF to start an engine, ATF tends to eat many rubbers. I don't know if the oil control o-rings or coolant seals are ATF resistant, but I doubt it.

It's used in piston engines because it soaks down past the rings (which are metal and therefore safe from ATF) into the crankcase, and then gets drained out.

In our case if used for carbon removal it will drain the bottom of the housing, but then below that is a coolant seal groove. Not to mention the oil rings on the rotor front + back faces as well. All of which are rubber.

If you're just pouring it in to build compression for a quick start after sitting a long time, it's probably inconsequential. But you could just as easily use motor oil.

If you're soaking it to dissolve carbon or something, I would advise against that.

As for ATF in the fuel, like I said above it's probably nothing. However fuel is cheap compared to a rebuild kit so I know what I'd do.

 

I would just drive it , but stay off boost for justin

 

 

I didn't want to use it on purpose. I just wanted to premix with Idemitsu oil but I accidentally used the ATF oil. I poured just 3oz to a half tank so I think that it is dissolved enough to not cause any trouble. Also today I filled up the up with high octane gas so now the 3oz are inside a full tank. I also premixed with Idemitsu oil. I drove the car today (un-boosted of course ) and had no problems at all.

 

Thats a good point about the rubbers though

 

My only question is why were you putting premix in at home and not at the gas station?

 

Because I had a 20 liter fuel canister full of gas

 

It is but many people in here disagree that it can dissolve rubber or even carbon deposits. I read a post that the rubbers were covered with ATF oil and left for a week or so with no signs of damage.