Engine oil flush recommendation.

[i6pwr]

I want to add to what others have stated about not using a flush. If you think about it, are you basing your decision on the dipstick and not knowing how the inside of the engine actually looks?

I would strongly suggest going about your cleaning request slowly over time. If it comes down to actually needing a flush, then you can cross that bridge later. The risk you run is dislodging large amounts of crud and possibly clogging the pickup screen if severe enough.

What you want to do is slowly dissolve whatever may be in there and filter it out. Using a synthetic with some MMO and changing frequently may save you some grief.

However to answer your questions, I've heard good things about the Amsoil flush, I've used Rislone before with good results. If the engine is relatively quiet, doesn't smoke, runs smooth....I would surely try the slower method first.

 

[The Critic]

I have used BG EPR and Amsoil Engine Flush before with questionable success. BG EPR seems to work a bit better, but I have not done any conclusive testing to validate this. The drained oil usually appears visually darker after using BG EPR and reeks heavily of a solvent. You can purchase cans of it on eBay.

 

[alcyon]

Define dirty. If its not sand or mud like particles and just darker colored oil, then no need to flush, just change out the oil.

 

[Linctex]

Originally Posted by Talent_Keyhole
....they leave 10-20% of the used oil in the engine for another full OCI. So this percentage will now have twice the hours and miles, which contaminates the new oil, and exposes the engine to higher, wear contaminents, sludge, and combustion byproducts.. Complete a full flush between oil changes.


Sir, I do NOT agree with this statement at all.
It is merely hearsay and there isn't any proof to support your claims.

The risk of leaving 10%-20% of the "old" oil in your engine each oil change is ZERO.

There is NOTHING that occurs that causes the calamity you claim that it does.

 

[MoneyJohn]

I quickly went through a few answers. While you are interested in an engine flush, which I get it (because I was there too), I went through the following options.

One of my vehicles was used roughly 3000 miles/year, almost all short trips, highly neglected with 90K+ on the odometer. I wanted to do a flush too but reading a lot on this board and many others, I figured, it may not be the best option. So I went with MMO first for a couple of (short) oil change intervals with Supertech Syn and a good filter. After that, I used Kano Lab's Kreen, regular intervals. (Trav has written some very good comments on a few threads regarding use of Kreen.) I have not pulled the valve cover but the car runs remarkably well. So if you REALLY want to do a flush, I recommend, go gentle first with MMO and then use Kreen. It should do the job. I recommend slow but steady. Making 100-mile trips at highway speeds may help as well.

Some places I was 'told', it may not be a good idea to perform a flush on the car like mine. I can't talk about your 100K vehicles but this is one data point for you to consider.

And dirty oil does not mean it is bad or there is too much 'dirt' in the engine. I am told that good engine oil suspends most of the carbon. If your oil looks dark, then the oil is doing the job it is supposed to do.

 

[RDY4WAR]

Originally Posted by Linctex
Originally Posted by Talent_Keyhole
....they leave 10-20% of the used oil in the engine for another full OCI. So this percentage will now have twice the hours and miles, which contaminates the new oil, and exposes the engine to higher, wear contaminents, sludge, and combustion byproducts.. Complete a full flush between oil changes.


Sir, I do NOT agree with this statement at all.
It is merely hearsay and there isn't any proof to support your claims.

The risk of leaving 10%-20% of the "old" oil in your engine each oil change is ZERO.

There is NOTHING that occurs that causes the calamity you claim that it does.


You always leave a small amount (0.5-0.75 qt) of oil behind in the engine with each oil change. It's puddled up in the head(s), crankshaft bores, etc... and you could leave your car to sit for 10 days to drain and it won't come out.

You'll often see two specs for oil capacity of an engine. New fill and service fill, with the new fill being 0.5-1.0 qt more than the service.

That said, this is not a concern whatsoever. Pouring in new oil for a quick flush is a waste of oil and you still won't get all of the old oil out.

As far as the color of the oil goes, black oil is not an absolute indication of cleaning. Oil turns black from oxidation. Contaminants act as catalysts for oxidation, but the oil will still oxidize without contaminants from normal heat cycling. It's very possible that the bottle of flush solvents is acting on the oil the same way as a sudden, massive dump of fuel dilution causing very rapid oxidation of the oil. It turns black very quickly, you think it's working, the flush company makes their profit, and everybody is happy... except the engine.

Also note that some ashless dispersants turn dark from UV exposure (from combustion events) making the oil appear black when it's actually not.

 

[Bill7]

Thanks for all your responses. I'll probably do an Amsoil engine flush 1 time, and then switch to Penzoil Ultra Platinum 5W-20 and change oil every 4,500 miles.

I was just reading the posts above about some old oil remaining in the crankcase after an oil change.

Is it a concern after an engine flush that some old oil will stay in the crankcase containing the engine flush chemicals, and that could damage the engine over the next 5,000 miles.
After the engine flush, Is it better to do a quick oil change with cheap oil and run the car a few miles and then drain it again (to get the last remaining remnants of the engine flush chemicals out)?

 

[Talent_Keyhole]

Originally Posted by Bill7
Thanks for all your responses. I'll probably do an Amsoil engine flush 1 time, and then switch to Penzoil Ultra Platinum 5W-20 and change oil every 4,500 miles.

I was just reading the posts above about some old oil remaining in the crankcase after an oil change.

Is it a concern after an engine flush that some old oil will stay in the crankcase containing the engine flush chemicals, and that could damage the engine over the next 5,000 miles.
After the engine flush, Is it better to do a quick oil change with cheap oil and run the car a few miles and then drain it again (to get the last remaining remnants of the engine flush chemicals out)?


Bill7, disregard the other posts claiming that no old oil remains in the engine or the residual oil does not have an affect on the new oil and engine. I have the VOA and UOA, and particle counts to prove it. After standard oil change 80-90% is drained out. After a second, 99% of the old oil is gone, along with any flush detergents or solvents. The term for this in the lubrication industry is Short Volume Oil Changes (SVOC). I always tell people to do a cheap flush, especially If using solvent flush, change the filter as well.. When engine testing labs evaluate oil for API certification, they typically flush the engine four times so there virtually no cross contamination of oil will occur..

 

[Talent_Keyhole]

Originally Posted by RDY4WAR
Originally Posted by Linctex
Originally Posted by Talent_Keyhole
....they leave 10-20% of the used oil in the engine for another full OCI. So this percentage will now have twice the hours and miles, which contaminates the new oil, and exposes the engine to higher, wear contaminents, sludge, and combustion byproducts.. Complete a full flush between oil changes.


Sir, I do NOT agree with this statement at all.
It is merely hearsay and there isn't any proof to support your claims.

The risk of leaving 10%-20% of the "old" oil in your engine each oil change is ZERO.

There is NOTHING that occurs that causes the calamity you claim that it does.


You always leave a small amount (0.5-0.75 qt) of oil behind in the engine with each oil change. It's puddled up in the head(s), crankshaft bores, etc... and you could leave your car to sit for 10 days to drain and it won't come out.

You'll often see two specs for oil capacity of an engine. New fill and service fill, with the new fill being 0.5-1.0 qt more than the service.

That said, this is not a concern whatsoever. Pouring in new oil for a quick flush is a waste of oil and you still won't get all of the old oil out.

As far as the color of the oil goes, black oil is not an absolute indication of cleaning. Oil turns black from oxidation. Contaminants act as catalysts for oxidation, but the oil will still oxidize without contaminants from normal heat cycling. It's very possible that the bottle of flush solvents is acting on the oil the same way as a sudden, massive dump of fuel dilution causing very rapid oxidation of the oil. It turns black very quickly, you think it's working, the flush company makes their profit, and everybody is happy... except the engine.

Also note that some ashless dispersants turn dark from UV exposure (from combustion events) making the oil appear black when it's actually not.


Oil may be puddled up in the crevices in the head or other flat areas, but the oil pump remains full, the oil galley leading up to the filter is mostly full, depending on the filter design and location, If you have a cartridge filter that is services from the top, several ounces remain in the housing along the main oil galley. Oil galleys remain full leading to the crankshaft. The oil galleys remain full inside the head. In my 2.4L with dual cams and VVT, there are three galleys with restrictor orrifice between the block and head. This is to keep the 16 hydraulic lifters, 10 cam journals, two cams, 2 VVT solenoids and the 2 camshaft actuators fully supplied with oil at every start up. I know because I have examined the head and engine up close while disasembled and noted the size of these galleys. They are large and are of significant volume. The days of 2-valve, rock arm style heads and single cam engines are over.

Who says this is not a concern? I have the VOA and UOA, particle counts, showing significant particulate contamination, 5x increase in wear metals, viscosity loss, TBN loss, and increase in oxidation caused by the residual oil after operating for 15 minutes.
Waste of money, hardly. Completing this $15, five quart flushing using API rated oil, will remove 99%, a second flush will rid the engine of 99.9%. Simple math. Use the flushed oil in your garden and yard equipment or if you have a old beater of grocery getter, or farm truck, use the oil in those. Don't spend $30+ on a new car just to repeatedly leave contaminated oil in the engine.

 

[Bill7]

If I understand you correctly, you are saying: add the Amsoil engine flush, run for 15 minutes, drain all oil, add new oil and filter, and that's it?

 

[Talent_Keyhole]

Originally Posted by Linctex
Originally Posted by Talent_Keyhole
....they leave 10-20% of the used oil in the engine for another full OCI. So this percentage will now have twice the hours and miles, which contaminates the new oil, and exposes the engine to higher, wear contaminents, sludge, and combustion byproducts.. Complete a full flush between oil changes.


Sir, I do NOT agree with this statement at all.
It is merely hearsay and there isn't any proof to support your claims.

The risk of leaving 10%-20% of the "old" oil in your engine each oil change is ZERO.

There is NOTHING that occurs that causes the calamity you claim that it does.



I doubt you even know the definition of hearsay. I have the evidence that within the first few miles, there are negative affects to the engine and new oil. . What proof do you have to support your claims?

 

[Bill7]

Sorry, I am missing the context of this. The current discussion is whether doing an engine flush, then drain the oil/solvents out, and then add new oil still leaves a small amount of the solvents from the flush in the engine mixed with the new oil, which over the next 5,000 miles will harm the engine.
Are you saying a 2nd oil change a few miles later would be required to get the remaining solvents out?

 

[Mad_Hatter]

Is there actually enough of the diluted flush left in the engine to have a meaningful impact on the oils chemistry? I'm not being facetious, I just dunno. I know with gas(ahol) it's about 2.5% by volume before it negatively impacts the oils properties like the flash point and film strength, no???

Wouldn't SAE and API provide enough range in it's specs to mitigate adverse effects of leftover solvent/flush???

I guess that's where a UOA after flush would be neat to see

(I've heard stories of using kerosene, or maybe it was toluene, in the crankcase as a cleaner with no ill leftover effects.. they just dump and fill)

 

[Talent_Keyhole]

Originally Posted by Bill7
Sorry, I am missing the context of this. The current discussion is whether doing an engine flush, then drain the oil/solvents out, and then add new oil still leaves a small amount of the solvents from the flush in the engine mixed with the new oil, which over the next 5,000 miles will harm the engine.
Are you saying a 2nd oil change a few miles later would be required to get the remaining solvents out?




Yes, It would also remove 99% of the original oil and contaminents. 10-20% of the original oil will remain in the engine after a basic drain and refill.. That includes the solvent based flush if used. Our modern engines with GDI and the inherent fuel dilution sometimes struggles to stay in grade for viscosity, without the added solvent left over in the oil. If you leave those solvents in even in 1-2% concentration with the fuel dilution from GDI will quickly degrade the oil and additives, reduce viscosity, and increase wear.

I recently got a courtesy, quick oil change from my dealer. Within 1700 miles, the oil sheared back to a 20W oil, TBN had dropped by 50%, and 25% of the wear metals were carried over.

Spend $15 on the second flush, and enjoy a full OCI, knowing 100% the additive package can be devoted to handling the contaminents from this interval instead of having to counteract the left-overs from the original oil.

 

[Talent_Keyhole]

Originally Posted by Mad_Hatter
Is there actually enough of the diluted flush left in the engine to have a meaningful impact on the oils chemistry? I'm not being facetious, I just dunno. I know with gas(ahol) it's about 2.5% by volume before it negatively impacts the oils properties like the flash point and film strength, no???

Wouldn't SAE and API provide enough range in it's specs to mitigate adverse effects of leftover solvent/flush???

I guess that's where a UOA after flush would be neat to see

(I've heard stories of using kerosene, or maybe it was toluene, in the crankcase as a cleaner with no ill leftover effects.. they just dump and fill)


Why would they make those accommodations when no major oil producer or auto manufacturer endorses the use of any of the solvent based flushes. GM warns against flushing most of their fluids with solvents, just for this reason. People will leave portions of it in the crankcase, and drive for 5K+ miles and then blame the oil or manufacturer when things go wrong.. API is only a trade organization and focus on minimum requirements, collecting tons of money for their seal of approval.

I have posted a UOA after my GDI engine reached 5% fuel dilution after only 1700 miles. After the oil change and 1300 miles , my GM spec, high quality 5w30 SN+ Dexos Gen 2 Full synthetic was a mid-range 20W, and lost half of its TBN.

 

[Bill7]

Another question that would be helpful to have answered. If no engine flush was used, but instead a full synthetic with excellent additive package like Penzoil Ultra Platinum 5W-20 was used, and oil changed every 3 months / 4,000 miles from now on,
how long would that take to clean out a dirty engine?

 

[kschachn]

It would depend on how dirty it is, and with what. How dirty is your engine and what is the "dirt"? Some varnish or sludge? Is it soft sludge or hard? How much? Have you determined it is even dirty?

 

[Bill7]

It was more of a general question. With a moderately dirty engine, can synthetic oil alone clean it in a few oil changes?

 

[Mad_Hatter]

Originally Posted by Talent_Keyhole
Why would they make those accommodations when no major oil producer or auto manufacturer endorses the use of any of the solvent based flushes. .

I have posted a UOA after my GDI engine reached 5% fuel dilution after only 1700 miles. After the oil change and 1300 miles , my GM spec, high quality 5w30 SN+ Dexos Gen 2 Full synthetic was a mid-range 20W, and lost half of its TBN.


Nowhere did I say that the API intentionally would make accommodation for a solvent (contaminant) in oil, what I said was that a particular grade, say 5w30, has a viscosity range (min and max) for both the upper and lower number. And it's this range that could allow the oil to tolerate a slight dilution but still be within the min and max for that grade. Of course if the oil in question is just above the mins, than fuel dilution could drop it's grade. An already thin 5w30 could drop to a thick 0w20, no???

I'm not the oil expert here, so forgive me if I'm not using the appropriate terms. I'm trying my best to articulate my point.

And fwiw, I have never used one of the severe flushes for a number of reasons. I've always used MMO or Rislone (left in the crankcase for the duration of the oci) whenever I [felt] my engine needed it. Maybe you do need to do a fresh oil flush after one of these solvent cleaners, dunno?? I was merely wondering aloud if there's enough of the diluted solvent left over in the engine after draining, to justify the cost/time of an additional flush???

And yes, scratch my API reference that was an error.

 

[jeepguy1]

Years ago, I went to a quick oil change place to get my oil changed. The guy changing my oil was trying to sell me an engine flush. He came over to me and said the oil was really black so he recommended an engine flush, I asked him which model cars did he change the oil on and the oil WASN'T really black, because I wanted to buy one of THOSE cars. He quickly understood that I am not a moron and that I knew his sales pitch was BS.