What would happen if I added transmission fluid to the engine oil?


Asked by Jun 22, 2013 at 09:52 PM about the 1998 BMW 3 Series 318i

Question type: Maintenance & Repair

My transmission was slipping so I
bought a transmission additive to
help. I then accidently added about
10oz of the fluid to the engine oil
reservoir instead of the transmission.
Will this damage my car?  What
should I do?

20 Answers

drain it out and consider it an engine flush...no damage was done unless you're takin' this motor into HARD service....no it's a flush...we're done, put the recommended on your door sticker oil in there...thanks~

1 out of 1 people think this is helpful.

have your transmission filter changed and new tranny oil put in at this point~


It was lucas transmission repair fluid.


It was lucas transmission repair fluid. Is it drivable?

1 out of 1 people think this is helpful.

if you could get to your drain plug and responsible way of draining it out of there ...really don't know from lucas other than "the prince of darkness electrical systems"...get rid of that...wish I could testify to it's excellence, but really know nothing about this oil, think I've seen the logo at racetracks~probably racing grade~

Michael Tutty

Do NOT run the engine. Get the oil drained and flushed immediately. I would have he transmission serviced properly at the same time. That ZF transmission is a sturdy unit if given proper maintenance, but a little neglect goes a LONG ways with it. Same with the engine. Looked after according to manufacturer's specifications and it will live a very long life indeed. Mess around with it and you are looking at a $15,000 repair bill.

2 out of 2 people think this is helpful.

don't like the Idea of "repair fluid" Michael...well neither do I....sounds to magical~

Hector Irizarry Duval

Repair fluid only gives you a little more time but if the tranny has internal damage you will have to repair some day. They do work some times

Hector Irizarry Duval

A little bit of ATF won't damage your engine but you need to change the oil on it. Bmw tranny are not user serviceable you need to have technical expertise to do that. I recommend to measure the oil level and complete it if needed first. Bmw says this oil and filter are for the life of the tranny but I sometimes change it anyway

Hector Irizarry Duval

Ther is no way to get new oil in the tranny from the top, is from under the car and proper tools,

oook...just like Me MINI~ a world of hurt and annoyance will come to you if you try monkeyin' around with these pressurized transmissions...fluid will spray out one plug and be empty at the other plug...have heard horror stories with the CVT...like Hector says "leave this to the professionals"~ reminds me of what the experts were sayin' about the twin-cam Porshe...you've got to be a German Old-GUY and have been working with these since their inception or you haven't a chance with the timing belt job...in fact you're in a world of hurt finding the replacement belt to begin with~

Jonathan Murray

You will have aclean engine Just run for a couple days let t work and your oil will be dirty just replace it some people clean in side engine with trans fluid it works couple dàYa Ok but not a long5time

1 out of 1 people think this is helpful.

How long would someone recommend to leave this in if I change the oil and oil filter and putut ATF in it?

Bob Beaman

1 qt. of ATF added to the engine oil and running the engine for 15 to 30 minutes won't hurt anything. It might even be a good engine flush, but running and engine that has only transmission fluid in it may cause serious damage in a short time. The lubrication properties of ATF are much different than engine oil. I would change your engine oil and get that Lucas stuff out of there as there is no telling what is in it.

1 out of 1 people think this is helpful.
Victoria Carballo

I have a 2015 dodge charger i accidentally pulled the transmission oil out and i put it back threw the dipstick. My car wont go faster then 25mph and sometimes it wont go in to reverese? What do i do?

2 out of 2 people think this is helpful.

I've been using Lucas Transmission Fix for years to drain/clean my wife's VW after draining the engine oil, never mixed it in hers though. I've been mixing it on my VW for 30000 miles and never knew it wasn't for my engine oil until I had a mechanic do the Lube change for me. He stated that it wasn't for the engine oil and Im now going to use the Transmission Fix to drain/clean the engine and mix the synthetic oil with Lucas Oil Stabilizer. FYI-I never had more than 15% Transmission Fix to engine oil.

James Shaw

I have just put over a ltr of transmission fluid in my 1969 sovereign 420 engine what do I do

1 out of 1 people think this is helpful.

James you will not damage the engine in your '69 sovereign. a small amount of atf in the motor oil will do no harm and will actually "clean the valves and can reduce noisy valve rain and carbon/sludge deposits) that said do perform a regular oil change to bring your engine lubrication to the proper spec,.


victoria, your transmission must be filled from the bottom. there should be a large fill plug that internally has a pipe riser that will fill the transmission to the correct fluid level. the unit is presumably in limp mode since it is not reading the correct fluid level. also the incorrect level will prevent enough fluid pressure from being built up to power your car in reverse. i would recoment doing a complete fluid flush. a machine is required. (and take it to a reputable small shop. the dealer will charge an arm and a leg and most of your first born for this service and the chain stores will only drain and fill the unit if they even change it at all. the correct machine will pump ATF fluid in as it is being removed thus changing the fluid in the torque converter as well as the valves and soforth. if possible ask to see the service being performed so you can verify it was done. it will also bring your unit to the exact right fill level.


to all i do not personally belive in the "hype" of the magical mystery formulas and fast fixes. while not always ideal there in no substitute for an actual diagnostic and (especially in the case of a transmission) mechanical repair. if your transmission is slipping burnt clutch packs is the most likely culprit. these can be changed and are very in expensive. (ex. i just completed a 2010 camaro clutch pack replacement (fluid and filters as well) and the parts totaled just around 100 dollars.) while there is labor to remove the transmission once done you will be good for another 100k+ miles without having to buy a new unit. the liquid fixes only add heavier weight oil and friction modifiers. the heavier weight will bring the ATF fluid pressure back up and return your correct shifting buy at the expense of over working the oil pump in the transmission. and the friction modifiers cling to all surfaces causing the clutches to grab again but at the cost of blocking the extremely small orifices in your valves and will in short order ruin a valve body (ie: $1,000++ dollars) same as lucas (for example) the engine restore is simply 50 or 75 weight motor oil that helps the build pressure to account for bearing wear but over works the engine oil pump which if it fails internally will destroy an engine will small bits of metal running through and ruining the bearing surfaces, oil galleys and valve seats etc.etc.

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