Transmission fluid as an engine flush?

guido4475

Not a Member
My girlfreinds son wants to use transmission fluid as an engine flush, as advice from a relative.What are everyone's thoughts and theories on this? Although the detergent in the transmission fluid sounds like a good idea, I don't think this is a good idea.
 

chefdennis

Veteran Expediter
Wow thats something i haven't heard in yrs!! It goes back to when dextron 1st hit the market because of the amount of detergent in it. You would run maybe a quart at the most in the engine with the engine oil for a few days before you were going to change it....not something you need to do today or would eant to. Todays oils have enough additives and detegents in them to do the same thing.... its just something an older mechanic might offer up, kind of like an old wives tale.... but not really needed...lol, dang i am getting old..i do remember this, but i was just a kid...lol 35-40 yrs ago....

Oh if he still feels the need, i certainly wouldn't drain the oil and fill the crankcase with atf and run it...
 

Andrew0580

Seasoned Expediter
I have seen it work real well on a gas motor. I would be to scared to try it on a diesel. It makes a good injector cleaner though!
 

greg334

Veteran Expediter
Well the question is why would you need to "flush" the engine anyways?

If you have changed the oil in a decent time frame and used a good brand, I can't see any reason other than using the car/van to go to the corner store and back (less than a mile of driving).
 

Andrew0580

Seasoned Expediter
yeah I did this on a motor that had a blown head gasket just to help get the milky residue out, if you plan on trying to flush out the crusty deposits it will probrobly just move them to a different spot in the motor and could cause damage like a clogged oil passage. Flushing a transmission is another big mistake. Just change the fluids and filters when you are supposed to and you will be fine.:)
 

greg334

Veteran Expediter
Well with a transmission there is a 'right' way and a wrong way. I learned that too. It is best not to mess with it.
 

guido4475

Not a Member
I failed to mention the reason why.He has a lifter that sticks once in awile on his 86 dodge pickup with a 318 with 41,000 original miles on the truck. It sat for awile without being run.It runs fine now, but once in awile the lifters clatter.I suggested putting new lifters in it and being done with it altogether.And I would think the trans fluid might loosen something up and clog a passage, galley, or the oil pump screen.
 

Andrew0580

Seasoned Expediter
Hate to make it difficult on you, but if you put new lifters in and dont replace the cam it will wipe off your cam lobes in no time.
 

Jack_Berry

Moderator Emeritus
never having done an engine flush i remember rislone making a flush for engines. why not use a product for that purpose?
 

guido4475

Not a Member
If it was me, I'd just get another engine, rebuild it, and then switch it with the old one in the truck,saving down time. But to each his own, right?
 

smokn72ss

Seasoned Expediter
personally I would advise against engine flushing unless you are prepping it for a tear down ...... that **** loosens alot of crap up in the engine only to later break loose plugging the oil filter/passages and trashing the engine .... without you knowing it till too late and bearings are wiped out.New lifters on the old cam should be fine .... its old lifters on a new cam you can't do ....I run delco diesel oil and cam break in lube when I am breaking in a engine/cam/lifters you need the extra magnesium and zink in the oil to ensure a safe break in. most of the normal valvoline, quaker state pennzoil have these removed for emissions reasons.
 

OntarioVanMan

Retired Expediter
Owner/Operator
Used a little bit of tranny fluid in the engine oil when in the cab business....seemed to keep the lifters from sticking as much since taxis do a lot of city driving and idling...don't know if it would help with all the hwy driving we do...
 

guido4475

Not a Member
This is for my girlfreinds son's pickup, not my van.

But another question is this, generated by something that Greg has mentioned on this thread, that there is a right and wrong way to flush a transmission. I was thinking about taking the van and getting the trans. flush service done to it. Or is it better to just drop the pan, and change the fluid/filter? And is ther a drain plug on the torque converter to get the fluid out of it as well?I want to put synthetic in the trans, so I will need to get everything out of it.Any ideas?
 

chefdennis

Veteran Expediter
Pulling the pan, changing the filter and draining the converter will do the job just fine.....whats left in the case won't hurt the new syn at all....if you really want to get adventurous, you could pull the valve body...but if you have never done it, id pass as it isn't really necessary...
 

greg334

Veteran Expediter
Depends on the trans.

The trans in my wifes van the converter can't be drained but the one in my truck can. My one car has two drain holes for flushing the converter.
 

guido4475

Not a Member
I was hoping that someone who has a Ford has done this before and can tell me whether or not My trans has a Torque converter drain plug, but I guess I'll have to crawl under there and check it out...lol.
 
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