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What Is THE ATF Oil Only Cap For ?

151K views 30 replies 23 participants last post by  mjpgolf1 
#1 ·
Under the hood of my 2003 325i with steptronic transmission, there is a cap that says ATF oil only. What is it for? I am reading that the transmission fluid needs to be checked and changed at the transmission. ??????
 
#2 ·
Read your manual to be sure. But that sounds like the Power Steering Fluid reservoir.
 
#9 ·
Why not power steering fluid?
it's a different grade hydraulic oil. they just want you putting in the normal type of power steering fluid in, our bmw's take the same automatic tranny fluid grade. although you can use Redline's synthetic brand.
 
#14 ·
well they probably won't be clogged just because it's there, it's diluted into the ATF. they could clog because of a chemical reaction with the ATF. not likely though.

what is more likely is a chemical reaction with the rubber seals in the PS system. seals are made to work with a specific fluid. you've just introduced another...
 
#15 ·
hi guys. Im new to this forum. I have also blundered in this area. I have a 320d msport bmw. 2003. And i have put engine oil in the atf part. However the amount i put in was about a capful as it was alredy topped up. Is this enough to be concerned about or will it still be ok?
 
#18 ·
Lion,

Para is almost always right...and I'm sure he is this time too...but, if it's not too late, meaning you haven't driven the car or tried the steering with car on, then you could just use a turkey baster (don't know what it's called in the UK) and remove the stuff in the reservoir and replace with what's called for in your manual (doublecheck bmw na online to be sure there isn't a new fluid)--I use Dex III. That means car has not been driven and you use another car to get the proper fluid for PS system.

Anyway, that'd probably be a decent alternative if you otherwise need to drive this car soon...but once you drive it, you just need to flush and bleed...think everyone here just removes a hose from PS pump...honestly not sure which one, but check the diys...many around.

Even if it'd actually do little harm, it's not worth the risk for the 1 hour of work it'd take to be sure.

HTH

Doug
 
#20 ·
Important: Always use the fluid type noted on the power steering reservoir cap. Steering racks designed to run on the pentasin fluids (usually green sticker that says 11S or something to that effect) will get damaged with ATF and vice versa. The fluid type is key to making sure the steering component seals function properly.
 
#22 · (Edited)
You should drain, repeat a couple times and don't worry too much about it. Both fluids are petroleum based and will mix with each other. ATF is a lower viscosity oil with different additives than motor oil, but no catastrophe in the lurking from mixing the two. In fact many people put ATF in the engine sump for cleaning purposes and to free sticky lifters. ATF is a highly detergent rich oil...ever notice how clean it leaves the places where it is leaking...it makes a good degreaser.

So, the worst you did is raise the viscosity of the ATF just slightly...change the fluid once or twice and forget about it.

Clarification (edit): Many people put AFT in the engine sump... I do NOT mean ONLY ATF, but rather add ONE quart of ATF when the engine needs a quart to top off. Then, run it that way for several hundred miles and change back to 100% engine oil.
 
#26 ·
Sorry to revive this very old thread.

Yesterday evening my 11 year old (?!) E46 overheated, first time this happened to me. So I parked it and thought I'd check the cooling fluid.

Maybe I should 'park' this story here for a second and explain the context. I know 'absolutely' nothing about cars, it was freezing 3 degrees and it was 2:30 AM and I was parked at a dark closed petrol station. If you cannot handle stories of a complete stupid guy then please do not read on, you will be seriously anoyed. Then again, if you fancy a laugh, maybe you should read on :-(

So I left home and I was driving a short distance on the motorway, no crazy speed (around 120 km/h) for approx 14 Km/9miles and was wondering why the indoor heating of the car did not come on. All of a sudden I see the temperature gage on the dashboard is in the red (and the red light underneath comes on). So I panic. 2 Km further by chance there is a closed service station. Now the only thing I know of cars is a) how to drive them and b) in the movies when a car overheats they open a knob, they burn themselves and steam comes out, they put water in and drive on.

So my car is overheating so I check the booklet in my car and see that there is only one knob for cooling flued. Turns out I was looking at the wrong engine for a 316i, not for a 323i. Not that the locations are completely different but I also looked if there were any other knobs I could get confused with and on the 316 there is nothing near, but on the 323 there is (although the booklet does not state what it is).

Now in my panic, nervousnes, darkness, cold, stpidness, I undo the wrong knob and feel in the hole. The booklet stated that there should be some kind of 'fill stick' to show how full it is. I dont see it so figure it is empty. Surprisingly the service station had not closed the water tap (freezing that night) and I fill an empty half litre bottle and fill the hole. After about 200 ml it is full. That is weird, and what is even weirder that it smells like some kind of thin oil what is in there. Back to the booklet and I find out that I was filling the wrong hole.

Back to right opening: I open the cooling fluid hole very carefully with gloves but contrary to the movies, no steam came out and I fill it with approx 1 litre of water, then the 'level stick' shows it is full and I stop filling

I then spend some time panicking what the other whole was that I filled and in addition I had dropped that knob and it was resting somewhere below the engine, where I couldnt see it. So I made a make shift cover for the 'other hole' and started my engine. The temprature had come down. to mid level and I drove my car a couple of times backward and forward in the hope the knob would shift place. At one point (and with the light of my mobile phone, which was now again charged enough to use it's flash light) I saw the knob at the bottom plate under the engine. With a stick from the bushes I was able to get it out.

I now closed the unknown hole and saw the obscure text "ATF oil only". So I think that confirms what I was afraid of that I ruined my (already overheated) engine by putting water amongst the oil.

So I everything closed again. I turn around and drive the 15 KM home. Underway the temperature gage, three times, for a very short time went to red, but then subsided within 10 seconds or so to mid levels, if I hit the clutch and let the car continue 'not in gear' for 15 seconds.

I just reached home (full of adreneline) and though I would share my experience before asking the question I had. I just read the booklet a bit better (it is easier in a heated home with proper light) and found that a 323 hold more than 6 litre of cooling fluid. So I cannot imagine that the 1 liter I put made any difference.

I obviously will not drive my car anymore and make an appointment with the garage so they can figure out what is wrong early next week.

However as I am a curious one (and dumb as you can read above :-( ), some questions:
- The first thing I noticed before the overheating and also afterwards is that the heating in the car does not seem to work at all. Can this have something to do with the engine overheating. Both never happened before so it seems likely.
- Through this thread I now believe I threw 200 ml water in the Power Steering reservoir. If I see that the guidance is already to completely drain it if you put the wrong type of oil in, I can imagine this holds 10 times more for water :-S. I assume however that I can still drive to my garage (8 Kms or so) and this is not THAT pressing that I need it towed?

Thanks for the noob help.
 
#28 · (Edited)
- The first thing I noticed before the overheating and also afterwards is that the heating in the car does not seem to work at all. Can this have something to do with the engine overheating. Both never happened before so it seems likely.
- Through this thread I now believe I threw 200 ml water in the Power Steering reservoir. If I see that the guidance is already to completely drain it if you put the wrong type of oil in, I can imagine this holds 10 times more for water :-S. I assume however that I can still drive to my garage (8 Kms or so) and this is not THAT pressing that I need it towed?

Thanks for the noob help.
Car uses engine heat to provide cabin heat though the cooling system

Get it towed, be prepared for expensive bad news
 
#30 ·
You'll flush your ps fluid entirely and refill with the specified ATF--here it's Dextron III...not sure about you, but go by the book.

We don't know why your cooling system is overheating and until you do you should tow it to the garage.

Or, buy tools and read here until you puke. All the instructions you need to replace the cooling system and/or just the parts that broke are here. Problem is you don't know enough to diagnose...so the best advice is to tow the car. You already did more than I think you should have. Get the cooling system fixed and then read up on how to properly check fluid levels and condition. Monitor them for a bit after your cooling system repair to ensure you didn't create a head gasket leak. I think you'll be fine...but you should tow. Don't risk the car to save towing cost...you could get stuck with head/head gasket repair cost--$1,000 usd and up...something like that.

GL...hth
 
#31 ·
Omg guys. This is great. I know it's not funny but it is. To the people putting oil in the power steering reservoir, please put the jug of oil and wrench down and from now on if anything goes wrong or needs done on your car, take it immediately to a mechanic, do not pass go and do not collect $200. (For those of you that don't get the last part there, that is a monopoly joke). Good luck gentleman.
 
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