engine flush/cleaner

[greenleg88]

what are the views on engine cleaners that claim to remove buildup and deposits in engines. something like this

 

http://www.amsoil.com/storefront/aef.aspx

 

 

are these true? how do they work? and what are some trusted/recommended ones...

[ferox]

I have mostly heard horror stories about these types of cleaners, but not Amsoil specifically.

 

I have used them a couple times in ea81's with good results, but I didn't use it exactly as directed. Obviously it's a solvent wash of the lubrication system. I used the cheap stuff that just says Motor Flush. I followed the directions exactly to do the flush, but after I drained out the the nasty stuff I left the drain plug off and poured some fresh oil in the filler spout to push a little more nasty out of the pan. I then put the drain plug back in, changed the oil and filter, ran the engine for 10 minutes to wash out remaining solvent then drained it and changed the oil and filter again.

 

It seems like a waste of 5 quarts of oil and an oil filter, but I think it did a good job of washing out any remaining solvent and a bunch more nasty stuff came out with the buffer oil change. It was a one time operation for each motor, and based on what came out I think it was worth it for a high mileage engine.

 

I have heard of this stuff ruining engines though, so if you don't have a lot of crud in your engine and/or don't wash out the solvent you could run into problems.

[nipper]

Subarus run well over 200 300K miles without flushes. They are mostly damaging to the engine. The do what they say, but can weaken seals by removing "dirt" (the stuff that is helping to hold the seals together). They can remove some stuff that is actually helping to fill gaps etc etc.

 

Any chemical flush in anything on a car can cause much more harm then good. Regular fluid changes will make the need for a flush unecassary.

 

I have no problem with flushing brake lines, transmissions and cooling systems with fresh fluid, as that is what the systems were designed for.

 

If you want to do a "flush" of something like the critical lubrication system, use seafoam, which has been proven to be safe for soobys (well only one person blew one up, he left the seafoam in).

 

Also if im reading this correctly, your doubling the cost of your oil change. Also they are saying to use this between thier name brand oil. Now if you read it carefully (i am on pain killers so a bit fuzzy today) they just knocked thier own oil.

 

Keep away, change your oil at more frequent intervals then sooby recomends, and you will never have a need for it.

 

nipper

 

PS - have you changed your pcv valve? That prbbly has a larger effect on having your oil get dirty sooner then "longer service intervals".

 

Now if this was a sludge engine (toyo or chrsyler) and depneding upon your mileage i may have a differnt opinion.

[aircraft engineer]

The instructions (add a can, let it sit and idle 10 minutes) are characteristic of a "butyl cellosolve" cleaner. Used to be more "common" for use in "sludged" engines. Trouble is that it cuts the lubricity down and flows thru the entire oil system. Engines will "die" from bearing failure if you drive it with that stuff in it - won't take the "loads" on the rod bearings mostly because it's a DILUTANT as well as a detergent.

 

The other common flush is a terpene additive (citrus oil - orange oil is the most common and one of them is called "citrus safe") where you would add a few ounces for 2 or 3 oil changes in a row and run it until the next change (but as I remember, the change interval was cut in HALF (3000 miles or so) - supposedly no adverse effects on the engine. Quite effective a de-gunking an engine, too. Terpenes are naturally occurring detergents and intense degreasers - it's why your hands smell "nice" after peeling oranges and are very very "clean" - it took all the oil right out of your skin (water soluble)

 

Too much information?

[EVOthis]

the only thing i have to say on this subject is....i have had pretty good results with seafoam.....after i ran about 1/2 can through with my engine oil....i think my engine idles and runs smoother than ever......than again 6 owners and almost 200,000 miles i dont think my car ever had a service like that.....just my opinion....

[idosubaru]

first - what car, year, make, model, engine and how many miles and why are you wanting to do this?

 

but in general it's not worth it on a subaru. if properly maintained the engines will last longer than the rest of the car anyway. not worth the risks (even though they are small).

 

to answer your question, *** yes they "work" *** but please read on to define "work":

 

yes, lots of deposits can come out of the car - but the key is that those deposits weren't hurting anything to begin with. pull off the valve cover on any car that has age or mileage....it's going to be black on the inside most of the time. that's the stuff that ends up in your oil pan if it's hit with powerful detergents. the deposits aren't on anything that matters or has anything to do with moving/sealing important internal engine components.

 

that's why it's dangerous...why dislodge every piece of particulate matter at the same time when 99% of it is completely benign?

 

if you suspect your engine is dirty inside the best thing in my opinion is to frequently change the oil, get the engine up to operating temperatures for a significant period of time (avoid only driving for short trips), and occasionally add a high quality cleaner like sea-foam.

 

there are no miracle pills for engines or mystic goopity goop about engines.....factory recommendations are made for a reason and with subaru you can expect high mileage and reliability.

[elmwood22]

I am with nipper on the use of seafoam. Used it on two of my subies, in the gas tank, thru the PCV valve and the engine oil (just for a brief period, approx. 1k) never a problem. Cars ran better with even a little more get up and go.......with 4 squirrels under the hood how much get up and go do you really have? I have had success with seafoam just add as directed. On my '95 it has freed the imfamous sticky lifter, can you say tick, tick, tick, tick. Good luck.

[mtsmiths]

Seafoam!

[bulwnkl]

I take a similar position as grossgary. However, I word it differently:

"Flush" products are not safe to use in an engine. The only safe thing I know of is called Auto-RX. I have used it myself in fewer than half a dozen applications. It is similar in concept to the terpene products aircraft engineer referred to in that it works slowly (several thousand miles to complete the cycle). This is a primary part of why it is safe to use. Also, it does not compete with the oil to lubricate. In fact, it is an outstanding lubricant itself.

 

Where I differ from many here is in whether a Subaru engine needs to be cleaned inside. My experience has been (and I probably have less Subaru experience than a great many people on this board) that Subarus get harmful deposits in them at least as fast as the general average engine. I do think that Subarus often mask the effects of those deposits better than some engines.

 

The most severe case I can tell you about is my '91 XT-6. It had very low compression in one cylinder and borderline in another. However, the car did not show particular signs of a problem. Once corrected, it was certainly a quicker car. One might have thought the engine was just old and 'tired' when I got it, when in fact the issue was harmful deposits.

 

So, personally I won't use any kind of 'flush' product. I've used nearly all of them in my life (they're mostly all about the same thing), and while sometimes they'll have a positive effect, they're just not safe, IMO.

[idosubaru]

The most severe case I can tell you about is my '91 XT-6. It had very low compression in one cylinder and borderline in another. However, the car did not show particular signs of a problem. Once corrected, it was certainly a quicker car. One might have thought the engine was just old and 'tired' when I got it, when in fact the issue was harmful deposits.

this is most likely due to the XT6 having HLA's, most likely one was not operating properly due to being gummed up. frequent oil changes will correct this too...but it might take 100,000 miles! detergents help free them up. in the case of HLA's like this seafoam or a more agressive use of ATF added to the oil will clean them. but then again...adding ATF to the oil is another similar argument.

 

HLA's do not tolerate dirty oil very well, it needs to be changed frequently to keep them operating properly. push rod engines are much more tolerating of poor oil maintenance, not that i recommend it obviously. some subaru's have HLA's, others do not.

[aircraft engineer]

auto-rx is one of the orange oil (terpene) cleaners. I forgot the name of the stuff, but the description above is accurate

[bulwnkl]

It's an animal fatty acid and lanolin ester base, but perhaps that means it has terpenes in it (as well).

[bulwnkl]

this is most likely due to the XT6 having HLA's, most likely one was not operating properly due to being gummed up. frequent oil changes will correct this too...but it might take 100,000 miles! detergents help free them up. in the case of HLA's like this seafoam or a more agressive use of ATF added to the oil will clean them. but then again...adding ATF to the oil is another similar argument.

 

Yes, it may have been HLAs, though there was no ticking sound change before and after because I didn't have any special ticking troubles. After I thought about it a bit it became clear that it would not have been an HLA stuck extended, because that would have meant a burned valve (which there wasn't). A thing I did not mention was the decrease in oil consumption. Thousands of miles of HD diesel engine oil had only the most minimal impact on that. Basically, at this point it seems to me that it was a ring deposit problem, but it may have been something else like an HLA.

 

ATF, while often reported as an engine flush, has essentially nothing in the way of detergent-dispersant compared to engine oils (especially diesel oils), so any positive impacts it has outside of the psychological really cannot be due to anything but coincidence, people using way too high a viscosity oil in normal usage, or something not related to detergency or dispersancy.

 

I do agree that high detergent/dispersant levels will help sticky HLAs tremendously. However, solvents are not similar to DDs, and though they may be effective for some things, they're just not 'safe' in an operating engine. They compromise lubrication far too much, they're too aggressive to many components, they can kick off chunks large enough to cause more damage, and they don't clean very thoroughly without disassembly and mechanical assistance. A nice fatty acid-ester mix will clean much better and more completely, and will let the DD package in your oil do its job to remove the gunk.

[WoodsWagon]

I have used ATF to great results in cleaning out engines. ATF has a lot of detergents in it, but it still has high pressure lubricants for the gearsets it normall oils. I helped revive an engine that had had 3 oil changes in 86,000 miles by flushing it repeatedly with ATF.

 

The key to flushing any engine is changing the filter repeatedly. What happens when you stir up a lot of deposits all at once is that the pump sucks them up and pushes them all to the filter. This is the point of the detergents in the oil, is to keep contaminants suspended in the oil untill the filter cleans them out. When a filter cloggs, like when all the deposits you just loaded the oil with hit it, a bypass valve opens inside the filter. This lets unfiltered oil, which is now full of the crap you knocked loose with the detergents, right into your bearings, lifters, and turbo's. This is what wrecks engines after people flush them.

 

Have a handfull of filters on hand, and change them often.