My son's 1995 Saturn SL1 had been poorly maintained -- maybe not maintained at all -- for many years before being put away in a barn at about 97,000 miles.

We have done quite a few things to it since he acquired it a couple of years ago and it runs good and gets great gas mileage for him.

The issue with it now (121,000) is that the inside of the engine must be really dirty and gunked up. Within 500+ miles of an oil & filter change the oil will be dark and thick. We've been using synthetic 20-50 oil and changing it every 3,000 miles but, after 8 oil & filter changes, if it's cleaning anything it isn't apparent.

I've been thinking about pulling the pan and valve cover -- maybe the head as well to put new valve seals in -- to give it a good cleaning. Even if I do that I won't be getting at the oil channels that feed the main and rod bearings which leads me to my question: "Is there an effective way to clean a badly gunked up motor without opening it up?"

I've spent a lot of time googling this issue and it appears that most of the posts are by people who know nothing, have no experience, and are quite happy to offer uninformed and useless advice. The majority of the responses are something like "Useless, dangerous, just change the oil regularly and you'll never need it." While that's pretty good advice if you have an engine that has been maintained and the oil stays pretty clean between changes, that's not the case in this instance. My issue is that the horse has already left the barn. It wasn't maintained -- probably exacerbated by sitting in a barn for 7-8 years -- and it is clearly very dirty inside and I would like to clean it as much as possible without pulling things apart.

Do any of you have any actual experience with these engine clean/flush products on an already dirty, gunked up, engine? If so, which ones, what process did you use and what results did you get?

Thanks in advance...

 

Howard, I have used Gunk Engine Flush in the past and been happy with the results. My Dad used to run a quart of transmission fluid thru a dirty engine for fifteen minutes after warming it up to operating temp. He said you didn't want to drive it with it in there, because the trans fluid is kind of gritty and could cause a little extra wear on the main and rod bearings. I've even known some guys that poured a quart kerosene in the crankcase and let it idle for about a half hour. Smokes like a frigging mosquito truck, but cleans stuff out!

 

Howard, be aware that there is a risk in desludging an engine. I am not going to try to discourage you from doing this because I am the type of person who would do this and have done it in the past. When I was in the Navy, used cars were all I could afford so this kind of thing was normal for me. But in order to minimize any potential damage, you do need to know the risks.

I have used Gunk Engine Flush successfully, but mainly on engines that had a sticking lifter. I have used transmission fluid for the same purpose too, but I would dump in a quart a few days before the scheduled oil change and drive around.

As a general rule, slower is better. If you get too much sludge or coke broken loose in your engine, it can clog up the screen on the pickup tube and starve your engine. What you are doing now is working, the evidence is the thick black oil you get on short order after the oil change. I would recommend that if you decide to continue on this course, use 15w40 diesel oil instead of the 20w50 synthetic.

The diesel oil is made to hold more soot and sludge because diesel engines produce a lot of both. Diesel engines use this oil and often last a million miles or more. Diesel oil also contains some elements that provide for better lubrication than car oil, but, those elements do cause the cat to deteriorate a little faster, but only a little.

The new 5w40 diesel synthetic oils do not have these elements so you could use that as well unless it turns out to be a little too thin for your engine.

Now if you are in a really big hurry, there is another option short of a complete rebuild. There are a couple of dangers doing this though. Remove the valve cover and remove the sludge mechanically. Most of the sludge in an engine occurs on top of the head, under the valve covers. When the engine is shut down, a lot of oil gets trapped there and has to absorb all the heat the engine is sloughing off through the head. This is where it turns to sludge.

You could remove the valve cover and discover that there is not an appreciable build up of sludge so you end up spending money on a valve cover gasket that you would not have needed, and if you don't get the new one on correctly, you could end up with an oil leak.

Or you could find a lot of sludge. Before you start scraping or brushing, locate the drain back holes and plug them up so that the gunk you scrape loose doesn't fall into the oil pan. Carefully scrape as much gunk loose as you can and remove it from the engine. A wet/dry vacuum cleaner would come in real handy here.

Then use a parts brush and solvent to remove the rest of the gunk, again keeping it from the oil pan, but do not use the wet/dry vac here unless you are sure the solvent you use is nonflammable and noncombustible. Finish up with rags soaked in fresh motor oil, motor oil is a really good solvent as it turns out.

Remove the plugs in the drain back holes and clean them out as best you can. Pour fresh motor oil over the whole top of the head and let it drain down into the pan. a couple quarts should do, then drain the pan. Install a new valve cover gasket and replace the valve cover, remove and replace the oil filter, return the oil plug and fill with oil.

Even after all this, you can expect a few more oil changes that will dirty up quick. If you keep getting a lot more oil changes that dirty up quick, you may have a lot of blowby from the piston rings. For that, you might try removing the sparkplugs and filling the cylinders with seafoam or a product called "Breakfree". Let it sit overnight or for a day or two. Besure that the pistons are all about the same position about half way up cylinder and also pump out any seafoam or breakfree before putting the sparkplugs back in and starting the engine.

 

Keith makes a very good point here. I agree with him 100%. If you have the time and money, his suggestion is a very good one. No need to rush it if you don't have too. Slow and steady wins the race, right?

 

A good point... What the OP is doing is obviously working...

 

About the only thing i would not agree with is actually using a synthetic oil as an engine flush.
On one hand it is a good oil And the weight selected is a good, depending of course of the average daily temperature you live in, the 20W50. A multi-viscosity oil is in part chose for two reasons. The first number, 20, is the lowest temperature you expect to see when starting the car. If you live most normal places 20 is a good choice.
Using an oil with the first number of 5 assumes you will regularly see 5 degrees when the car is started. If you live in some place like Alaska it is a good choice. As I don't there is no way I am ever going to use an oil that starts with a 5 and that is the primary reason why so many people are complaining of excessive oil consumption. Using and oil on a regular basis that is way to light to properly lubricate your engine long term taking into account age and miles and the fact the warranty has now run out.
The last number, the 50 from a 20W50 is a perfectly good weight to be used through out most average climates according to oil viscosity (weight) vs temperature charts. But if you live where freezing weather can be regularly seen a 40 or a 30 is more acceptable. That said, I live where 1/3 of the year the daily temperature will be over 100 degrees and it rarely if ever gets to freezing. Thus I use 20W50 year around on all of my cars. Unless I am using Mobil 1 synthetic which is 15W50.
As to engine flushes.
There are commercial products out there.
Nothing wrong with using one as directed.
Also the back yard approach of a quart of transmission fluid, Diesel fuel or Kerosene plus 3 quarts of oil is an old school and effective way to help clean out your engine.
Nothing is magic. As pointed out excessive gunk is a problem of it's own.
After 8 oil changes the odds of excessive gunk being a problem is reduced.
The concern with any of these things is driving the car normally for any length of time with the witches brew mixture in the crank case is discouraged. A half a dozen reasons are brought up, the biggest being the engine will not be properly lubricated and if strained may damage something and the operative word is may.
So to be smart it probably would be a good time to do this just be fore a regular oil change, just add a quart of magic elixir to the crank case after the engine is warm, let it more or less idle for 20 min and then go ahead and change the oil.
Using a synthetic under these circumstances is probably pretty much a waste of money but it is your money.
I would not use a synthetic and don't just for that reason.
Dinosaur oil words just fine.
If I wanted to do this from fresh I would by the cheapest 30 or 40 straight weight oil put 3 quarts plus a quart of magic elixir and a new filter in, run it for a half an hour and change it.
To the oil you would normally use.
Synthetics keep engine crud in suspension better than dinosaur oil which in some cases is a benefit. Good or bad, after the same amount of miles the synthetic oil will look dirtier than dinosaur oil If it does, it is normal, it means it is doing it's job.
A "Flush" is trying to catch all the engine crud in the oil filter so you can throw it away.
Particle size of the crud says what will be captured by the filter vs what stays in suspension.
When you change oil, it is recommended that the engine be warm.
Why
because fine crud will not have time to settle out of dinosaur oil and go out when it is drained.
Synthetic tends to keep fines in it if the are not trapped by the filter.
Again your choice as to dinosaur vs synthetic, but the cost effective advantage of synthetics is that if you keep a fresh filter in it every 3 to 4 thousand miles and just add enough oil at that time to replenish what is used by changing the filter, it will properly lubricate your car for 12000 miles more or less.
Where as dinosaur oil want to be changed out about every 3 to 4 thousand with the filter.

 

Thanks for taking the time to offer that very detailed post -- I appreciate it.

I may still tear it down -- I'm really suspicious of the valve stem seals -- and will do a complete cleaning if I do. But until I do I'll just keep changing that dirty oil out regularly.

Yesterday I added a can of Seafoam and let the engine idle about 30 minutes before changing it. Unless someone knows of a product more effective than Seafoam that's what I'll use the next time as well.

Btw, you make me curious. I've always thought of the filter change being the add-on to the oil change. Your post makes me think I could look at it the opposite way as well. Just change the filter and maybe, or maybe not, change the oil too. Right?

 

Seafoam has a good reputation, but the product to avoid is AutoRx. It turns your oil black once it is heated so it looks like its cleaning your engine, but its not.

Edit, there is no big rush on this. If the lifters are not stuck, then the sludge isn't in a place where it can do any harm as long as you keep up the oil changes. It will only get better with time.

 

I understand the point you were making and appreciate the detailed explanation. When I was growing up [back in the 50s and 60s] the filter was only changed every other oil change which is why I described it as an add-on -- oil change + filter change.

 

Back in the 50's and early 60's, the oil change interval was 2 months or 1500 miles, and then you had to throw in the "lube job" for another $2.