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Engine and transmission flushes are being sold left and right, but are they a good idea?
A New "Recommended" Maintenance Item...
In the last few years you were probably asked, or told, by you dealer or quick lube place that you need an engine or transmission flush, because the engine oil or transmission fluid is very dirty. They will tell you that it is recommended that you have it done because your engine or transmission will last longer if it is flushed clean. In that they are correct, a clean engine and transmission will last longer. But is flushing the best way to get a dirty engine clean?
What Is An Engine Or Transmission Flush?
Flushing is the high pressure forcing of fluid back against the normal flow of the fluid. In other words if the normal flow is left to right, the flush would force the fluid right to left. This is accomplished by connecting a machine that will force special solvents back through the engine and transmission. The idea is that by forcing cleaning solvents backwards through the system, it will get all the junk and garbage that has formed over time and "flush" it out of the system. In theory this may be sound, but in actual practice, it's dangerous.
The Dangers Of Flushing...
Flush machines do what they say; they force high pressure cleaning solvents back through the engine and transmission and clean out some of the accumulated junk that has formed. Now engines have small passages and galleries through which oil or automatic transmission fluid flow and there are one-way valves that keep the fluids from backtracking for whatever reason. By using an aggressive cleaning procedure like flushing, large chunks of accumulated sludge are broken off and forced backwards through these galleries and valves and, more often than not, lodge tightly and block them. This cuts off the normal flow of the fluid and causes lack of lubrication in an engine and abnormal or no shifting in a transmission. The results are expensive repairs, or more often, engine or transmission replacement.
Who Recommends Flushing As Maintenance?
The shops that want to sell you the engine or transmission flush charge anywhere from $49.95 to $99.95, not including a new engine or transmission. Those are extra. And they state quite emphatically that it is recommended that it be done. But who actually recommends that it be done? I checked with GM, Ford, Chrysler, Nissan, Honda and several other new car manufacturers and not one recommended an engine or transmission flush as routine maintenance. In fact, they specifically don't recommend it at all!! The new car dealerships that do sell them use the implication that since they are the dealer that it must be the factory that recommends it. And if they do say the factory recommends it, they are flat out lying to you.
The only ones who do recommend flushing as a maintenance procedure are the companies that sell the flush machines and the shops that buy them. The flush machine manufacturers state quite clearly in their operating manuals not to use their machines on "high-mileage vehicles". That simple statement proves that flushing is not a safe procedure. It also absolves them of any responsibility of any damage that may occur due to the use of their equipment. This leaves the shop wholly responsible for anything that happens and the cost of correcting the damage that occurs.
I know this since I recently appeared as a witness in a lawsuit where a person was sold an engine flush that destroyed his engine.
The Facts...
The fact is, if you do frequent engine oil and filter changes and service the transmission every 15,000 miles there is no need for a flush. I have customers that change their oil every 3,000 miles and they don't need to use fancy oils and filters, and after over 100,000 miles, the oil comes out almost as clean as it goes in. They have regular transmission services and their transmission still shifts like new, even with well over 100,000 miles on it.
If you have neglected regular oil changes and you want to do some interior engine cleaning, get the oil and filter changed and replace one quart of motor oil for one quart of transmission fluid. The transmission fluid has a high detergent content that will clean the engine without damaging it. Do this every 3,000 miles and you will clean the inside of the engine slowly and gently.
If you do get a flush, I recommend you do it when you can afford to replace the engine or transmission.
The copyright of the article Do You Need To Flush? in Auto Tech & Repair is owned by Vincent Ciulla. Permission to republish Do You Need To Flush? in print or online must be granted by the author in writing.
Comments
Mar 31, 2007 9:08 AM
Joe Marion :
One of my inner bearing for my cams on a 1999 twin cam Harley Davidson went out. with it my oil pump was damaged also. Is it possable to flush all the debri from the crank case with out pulling the engine?
Jun 12, 2007 7:21 PM
Keri Walker :
On May 19th I took my 1991 Aerostar to Mr. Lube to get an oil change. As it had been awhile since I had one the Tech had "strongly" advised me to get an engine flush - telling me it would clean all the sludge out of my engine and it would perform better. I agreed to it and after the oil change I came home and did not drive my van again until the next day when I went out to my mother-in-law's. An hour and a half into the drive my engine starting making loud clunking noises. I had to get it towed back into town to my mechanic who said I had complete engine failure. I had told him about the flush and asked if this could be the cause, since I have never had engine problems before, and he said it most likely was. The co-owner of the garage also told me years ago he had a 1990 vehicle that he had himself done an engine flush on .... one week after the flush the engine completely ceased.
I had to have my van towed to another shop who could put in another engine for me and both mechanics there said it was for sure the engine flush that caused my engine failure. They said that what happens is the "sludge" in the engine that builds up over time becomes loose when this chemical in the flush is released, and the debris then destroys the engine. Had I not had the engine flush.. I would not have needed a new engine. I called Mr. Lube to discuss this problem with them and they advised me that "someone" would call me back but no one ever did. I finally contacted the head office in BC and asked for the names of the owners of Mr. Lube and was given Mr. Jason Guenter. I contacted Mr. Guenter and he first wanted to know why I hadn't called Mr. Lube more than once to report my issue...???? I told him that I never had engine problems before and he was more than welcome to contact my mechanic to verify that. He's now coming up with one excuse after another about why they should not take responsibility. I just want compensation.. with the towing charges, rental of another vehicle, a newer engine and the labour my costs have exceeded $2500.
Jun 20, 2007 10:37 AM
Steve Taylor :
This is a very misinformed post. As a Ford Master technician and an ASE Master technician with 15 years experience and 5 years of transmission repair experience I find this article very simplistic and one sided. Most transmission failure is due to no fluid replacement. Many manufactures are sealing their transmissions and calling them fill for life...this has, in part, been successful due to the transmission fluid exchangers. Ford 4r70w's (Crown Victoria, Explores, Thunderbirds) are notorious for torque convertor shutters going into overdrive the known and manufactured suggested repair was a fluid exchange that would replace all 16 quarts in the transmission. I have owned these vehicles and maintained them with transmission and coolant flushes every 30,000 miles and had more than 200,000 without major issues. The replacement of petroluem based fluids on a scheduled makes sense. The sludge described here does not happen on a properly maintained engine or transmission (although some friction material in a transmission is normal). Talk to a modern repair facility with certified technicians for advice. There are enough conspiracy mongers out there.
Jul 10, 2007 5:11 PM
Peter Ruggeri :
Hello,
I am not too familiar with cars ata ll. I have a 1993 Cadillac Deville and was recommended to have a transmission flush when my oil was changed. The tech said that even when he changes the oil the dipstick still comes out black because of sludge in the engine. He quoted me a price of $150.00. Is this an accurate price? The car has 75,000 miles. Originally, the car had about 69k when I bought it. The car only had one other owner. Should I trust the facility that does my oil change or go to the dealear to have the work done?
Thanks
-Pete
Oct 15, 2007 3:37 PM
DBuilder :
The post is not misinformed, it is spot-on accurate. With all due respect for your position and experience, I work for the manufacturer.
Back flushing engines and transmissions are NOT recommended for the reasons stated in the article.
Jan 25, 2008 8:58 AM
tino z :
I think what the original poster was referring to was backflushing the transmission by force. In a fluid exchange you usually push out the old fluid while putting in new fluid which would not affect the transmission at all. All you are doing with a fluid exchange is changing out the fluid. the new machines do this through the dipstick where they remove 2 quarts and then put in two quarts until the fluid is clean. they usually run an extra amount of fluid to accomplish this. On my windstar they put in 16 quarts to flush out 12. the extra was to make sure that the fluid was nice and clean.
May 2, 2008 10:53 AM
Guest
:
DAMNIT!!! I wish I would have read this last year. The guy at Walmart talked me into doing an engine flush. He "hooked me up," and did it twice because my engine was "really dirty." well, my engine went out on me a few months later. Now I know why. DAMNIT!!!
May 5, 2008 10:49 PM
cameron :
yea the original statement is talking about backflushing. when you get a transmission flush they have a machine that consists of a tank of cleaning or detergent that isnt pressurized at all. it is hooked up to the transmission line and the transmissions own pump circulates the fluid. there is no high pressure like you see in the aamco commercials. the detergent goes in then the old comes out until the detergent flows solid. then the new fluid goes in until it flows out solid then theres a new filter and gasket installed at the pan and everything is sealed back nice and correctly. don't get confused about that false statement above. also, engine flushes are different. there are oil additives where you pour it in the crankcase and let the car/vehicle idle for a certain time and then you drain and put on new filter and new oil. then they have other ways with different detergents that eat the gunk away and free up passages. Now for radiator flushes. they drain the old fluid. run a special detergent that gets any gunk out and you use your engines pump once again like the trans and engine flush. there is no high pressure backflow. I have done a engine flush and coolant flush. next is trans. The reason why a trans may die after a flush is because you didnt look at teh fluid first. if its dirty and burnt looking/smelling dont flush the trans because its toast. if you flush it it will die if your fluid is that bad. the reason your engine probably died was most likely because either the guy that did it did something wrong or your engine was bound to go. you need to change the fluids. theres a reason why these methods are done. because that is how you do it. you dont just add more. you dont just drain it and expect it to all be out either. you flush it. dont get confused. have some sense in what you do and dont immidiatly blame a flush when it wasnt its fault.
8 Comments
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