While we here at EngineLabs try to deter our readership from cutting corners, there is no denying the fact that “stop leak” additives are here to stay. From the U.S. military’s widespread usage of Marvel Mystery Oil during World War II to the advent of the undeniably ubiquitous line of products claiming to be a “repair in a bottle” line the shelves everywhere you look.
However, being that most drivers are entirely too busy (or flat-out “mechanically challenged”), conducting an engine teardown just to replace a gasket or a few leaky O-ring seals is completely out of the question for them. Being that gasket, seal, and O-ring replacements also require a significant amount of financial investment, the appeal of an inexpensive quick fix remains quite alluring to many.
But do these self-proclaimed “stop leak” products actually work? If so, how well? And perhaps more importantly, what happens when they don’t work as advertised? Will they bludgeon our precious seals faster than a boatload of money-hungry Alaskan fur traders in the late 1800s?
I guess we’ll just have to find out…
Not too long ago, Todd over at Project Farm LLC released a comparison video, where the unbiased (and outright enthusiastic) YouTube product tester pitted fourteen engine stop leak products against one another. A video that the clever content creator claims were intended purely for “entertainment purposes,” and did not influence the contents being placed in shopping carts across America.
But before meeting Todd’s contenders, his methodology for testing these products must first be examined. Which in true Project Farm fashion, are equal parts effective, well-illustrated, and strikingly simple.
The goal of the test was straightforward: Compare a handful of stop leak products and determine their ability to condition/soften hardened rubberized engine components, with brand-new parts like gaskets, O-rings, and seals being the primary focus.
Resistance to evaporation during normal engine operating conditions while providing adequate lubrication and cooling was also taken into consideration, as was viscosity in cold conditions, and wear and tear on metal-to-metal contact points.
As with any Project Farm comparison test, a slew of products were selected, with Todd opting to put fourteen additives through the proverbial gauntlet this time around.
While there are a ton of other oil additive options to choose from out there, time constraints kept Todd’s findings focused on some of the more common products you’d find down at the local auto parts store, along with a few online oddballs thrown in for good measure.
Some of these products proclaim that they are intended purely for engine oil enhancement and seal repair purposes. Whereas others boast that they have the power to fix leaks and lubrication issues within differentials, transmissions, power steering systems, hydraulic units, and more.
In the case of this particular Project Farm test, Todd’s contenders included:
According to his introduction within the video, Todd’s key focuses remained zeroed-in on the following considerations:
Oil viscosity
O-ring “rehabilitation”
Impact on new O-ring resilience
New engine component safety
And like any mad scientist worth his salt, Todd began his testing with a control. In this case, this meant using a 40ml dose of full synthetic Pennzoil 5W-30.
For the metal-to-metal comparison test, a simple belt-driven lathe and grooved wheel making contact with a steel pin was the tool of implementation. After measuring the diameter of the groove and the energy exerted via the use of an energy usage meter, each oil additive was put to work.
During testing, a 50/50 blend of stop-leak and the aforementioned motor oil was implemented in 30-second testing increments to prevent excessive damage from poorly performing products.
Each test was then followed by an inspection with a microscope and a set of calipers to confirm the effectiveness of the product in regard to reducing (or increasing) wear-and-tear on the metal pin contact point. Furthermore, a new mixing straw was used for each brand to eliminate any cross-contamination between products.
In between each round of testing, splashes of brake parts cleaner and a quick resurfacing of the test wheel with sandpaper removed any residue or grooves leftover from the previous round. Thus guaranteeing a fresh surface after each round, regardless as to how much metal was shaved off, steam was emitted, or splashing occurred.
After conducting the metal wear test, Todd placed each blended test sample into a freezer to see if those claims that “engine viscosity will not be affected” were true or not. Naturally, there were some clear winners and failures, with a 24-hour cooldown period in the freezer resulting in certain products performing better than the straight motor oil, while others merely turned to sludge, or worse yet, became frozen globs.
While all fourteen blends were chilling in the deep freeze, the O-ring testing portion of the gauntlet was taking place. Naturally, brand new gaskets were utilized, all of which were first measured and then dropped into 100-percent straight stop-leak test cups for 48 hours at room temp. Todd explains that he did not blend the additives with the motor oil for this stage due to the separation that was observed with certain products.
As the O-rings soaked, a standard strip of gasket material and a bunch of brand-new O-rings were dropped into a beaker (a.k.a. coffee pot) of motor oil that had been heated to 350°F for 2 hours.
A quick durometer test showed a much harder O-ring, with a material circumference that was about 6-percent thinner than prior to the heat treatment that had just been implemented. After throwing the heated O-ring seals back into a blend of each product with the motor oil, everything was weighed once again and reheated for two hours to see if any of the rings could recover.
After weighing, results showed that the straight synthetic motor oil only lost 0.02 grams during the entire 2-hour heat cycle. Now as for the additives and how they faired, this side of the examination was pretty polarizing. Heavily evaporated products provided respectable O-ring protection, while heat-resistant samples didn’t do much if anything for the rubberized rings.
As the final results chart above clearly illustrates, unheated O-ring soak times were also intriguing, as many products didn’t make a bit of difference in the durability or size of the new ring in question, while others did help the rubber to slightly soften and expand.
Being that gaskets are just as important and widely utilized as O-rings within a combustion engine, this form of material too had to be put through its paces. While we are not entirely sure as to what type or thickness of gasket was used, Todd explains that it was an unused item that had merely been cut into strips for usage.
While the whole O-ring boil side of the experiment was taking place, those strips of boiled gasket returned their own round of results. A quick poke with a pick and a press resulted in the scales showing a few products out in front in the gasket puncture test, with others performing miserably.
Torture testing complete, and findings all tallied up, the top performing stop leak additives included SealLube (which coincidentally was also the priciest product tested) and ATP’s AT-205.
Whereas the SealLube didn’t do well when it came to reducing wear, it practically dominated in almost every other category, including the O-ring comparison test, heat comparison showdown, and viscosity rankings.
The only other product that was able to best SealLube was the AT-205, which came out on top thanks to its superior wear resistance and O-ring rejuvenation capabilities.
Now as for the rest of the pack… let’s just say that they either did an alright job, or flat-out failed to deliver when it came to lubing up those dark black donuts or reducing heat-related wear and tear.
If you want to see all of the raw data, make sure to watch the video. We’ll post up our takeaways from each of the fourteen findings below and let you mull over what was discovered. Either way, we tend to steer clear of stop-leak type products in general, instead opting to fix things the proper way, and therefore view these types of tests for what they are intended to provide: Pure entertainment.
ATP AT-205 “Re-Seal”:
Settled at the bottom of the container and needed remixing prior to testing, and was literally steaming hot after the metal wear testing stage was complete. However, it managed to redeem itself by returning the O-ring almost to its original size and making it even softer than new. It also scored very well in the freezer viscosity test, earning it the top spot as the overall best-performing product.
Bardahl “NoSmoke +Stop-Leak”:
Very thick and therefore performed extremely well in metal testing and did not evaporate under heat, but didn’t do diddly-squat for O-ring repairs.
Liqui Moly “Pro-Line Oil Loss Stop”:
Provided less wear on the wheel and lowered friction, but evaporated a lot during heat testing. And while it did soften the O-ring slightly it did not restore its circumference, and almost froze solid during viscosity testing.
Lucas “Engine Oil Stop Leak”:
Requires a 1:4 blend ratio with motor oil and did alright, with O-ring testing being very close to that of the Bardahl stop-leak. Viscosity testing and heat treatment were just alright, as were gasket puncture test results.
Bar’s Leaks “Engine Oil Stop Leak Concentrate”:
Created more friction and wear and zero change to O-rings after heat testing. A middle of the road contender that did more harm than good overall.
Lubegard “Seal Fixx”:
Kept separating from the motor oil and caused loads of damage and evaporation, but did help restore some O-ring circumference and returned the ring to its original hardness level.
Hapco “Pro-Seal”:
Medium amounts of damage despite blending well with the oil, and served as a decent O-ring restorer.
Blue Devil “Oil Stop Leak”:
Separated almost immediately and created a reasonable amount of friction, it also boiled off a lot during heating, but helped some during O-ring testing. Another product that seemed to provide more risk than reward.
XADO “Engine Oil Stop Leak Concentrate”:
Only product on the roster that was made in Ukraine, which performed poorly in the metal friction stage, with mediocre evaporation and O-ring results.
SealLube “Seal Expander”:
Most expensive product tested ($35), and didn’t do well at all in regard to wear, but dominated in almost every other category, including the O-ring comparison test, heat comparison test, and viscosity ranking.
Promeko Inc. “Snake Oil”:
Pretty significant wear damage, but surprisingly, not the worst either, even though it didn’t help O-rings at all after not boiling off one bit.
CD-2 “Heavy Duty Sealer”:
Lots of damage to the metal pin, but little evaporation and slightly softened O-ring results, even though it couldn’t help the seal expand much in size.
Justice Brothers “Engine Stop-Leak”:
Became very hot and vaporized into steam, with the same metal pin damage ratio as the CD-2 product. It also boiled off the most during O-ring testing, yet somehow restored the O-ring’s size and softness to near original specs.
Wynn’s “Engine Oil Stop Leak”:
Made in Belgium, and blends well with motor oil, but it created the largest wear scar at 9.35mm during metal testing. However, it did fairly well during O-ring heat testing, and was dead center in the gasket puncturing challenge.
View Full Version : Preventing Valve Stem Smoke! Best Oil?
AC75
What oil does everyone with the smoking valve stem issue use? Is there any formula that will help reduce the smoke even a little?
Newave Dave
Synthetic oil seems to cause less visual smoke.
SignatureSeriesOwner
There's no real way to prevent it. It's a factory defect, and it'll pop up whether you used dollar store oil, or Mobil 1 from the first oil change.
A thicker oil will help lower oil consumption, the the issue lies with getting the thicker oil to the top end of the motor quickly enough on colder days.
While the motor itself may have increased bearing tolerances and such from when it was new, the oil passages haven't.
AC75
I know I can't prevent it, and I doubt I'm ever going to invest in fixing it, but I had an oil leak repaired a few weeks back and I really don't know what type of oil they put in the engine after to top it up. But it does seem to put out more smoke than whatever was in there before the leak. I only bought this car a few months ago, so I don't really know what was being used before then either.
If I start using all synthetic, is there any point in a full oil change, or should I just keep adding synthetic when it needs a top up?
Newave Dave
AC75, IMO using synthetic for self service oil changes is a no brainer. You can get the five quarts and a Motorcraft 820S filter for about $25. Less then that if you keep your eye open for sales and rebates. If you go to Quicky Lube that's what they charge for the change with dino oil. If you change it yourself using dino oil you may save $10 per oil change. So I would buy a couple jugs of 5w-20 Mobil-1 at Wally World and change your oil.
AC75
OK, that's what I do. May as well get it done before it turns cold and shit fall arrives.
Side note: why is it that there seems to be way more smoke when I move the car after it's been idling for a while? I don't just mean under normal acceleration from stop, but from idling.
A while back I had a flat battery and so to stop it from draining after a boost I let the car idle while I had the doors open cleaning junk out of the back and the trunk. Maybe 5 minutes, 10 max. When I took the car for a drive straight after, I noticed there was an abundance of smoke for the first 5 seconds on the road then it went back to how it always is - smoke under acceleration.
Does more oil get into the combustion chamber at idle or something?
markedman90
Does more oil get into the combustion chamber at idle or something? The technical term for that is called "slobber" - REALLY
Depending on where you're located, you may want to go to a straight wieght oil. 20W or a mix of 20/30W. There are fewer additives (viscosity stabilizers) than in multi-grade oils.
This is just my 2 cents, but it has worked for me on pushrod engines w/ bad guide seals.
Dusty
I have been using 10w-40 high mileage oil. I use a quart every 3k miles. Seemed to help quite a bit over the 10w-30 standard oil. I have been doing this for 9 years and 90k miles. I have noticed no change in consumption over that time. 95 TC has 205k miles on it.
I usually use Mobil 5000 high mileage oil.
AC75
The technical term for that is called "slobber" - REALLY
Depending on where you're located, you may want to go to a straight wieght oil. 20W or a mix of 20/30W. There are fewer additives (viscosity stabilizers) than in multi-grade oils.
This is just my 2 cents, but it has worked for me on pushrod engines w/ bad guide seals.
Slobber! That doesn't sounds very technical, does it?
Tennesseestorm
I use 4 quarts of 20w-50 oil and one quart of Lucas™ engine restorer. I have used it for the past 3 or 4 oil changes and BARELY notice any oil useage between changes and no smoking from exhaust, even after setting at long traffic lights/drive-thrus (and my car has 220,000 miles). This last time I have went almost 5000 miles (I usually do 3000-3500 mile changes) and I think I had to add about 1/2 a quart. It is $11.00 per bottle, but worth it.
gadget73
Thick oil is an incredibly bad idea with these engines. It won't pump to the top and will cause the heads to be destroyed. These don't have cam bearings. The cam rides on a film of oil in a saddle machined directly in the head. Steel cam, aluminum head. The head will not survive without sufficient oil in there.
TobyU
I know everyone says you will cause damage with thick oil, but I ran mobil 1 15w-50 red cap in a 92 town car with 117,000 when I bought it.
I ran 15w-50 until I sold it at 208,000.
Im Ohio climate.
I was concerned when it first got cold out. Back then I think I read about some oil filters expanding blowing out due to high pressures with thicker oil. Didn't rear too much about the head/cam issues you see always mentioned now.
This was in 2000.
We also ran the mobil 1 15w-50 in at least one other town car. It was a 95 model in 1999. It had 180,000 on the odometer but had a jasper reman in it. No history on the miles on the reman engine, but it had quite a bit of valve stem smoke on take off after idle.
The thicker synthetic helped about 40-50% with the amount of smoke.
Never had any engine problems with either one with the thick oil.
But 15W-50 full syn is a lot different than 20w-50 regular oil.
20w-50 dino is like molasses below freezing. I have put many oils in the freezer to watch the pour when I take them out.
I would not put 20w-50 in a Ford modular unless the temps were always 60+
It is still darn thick on start up.
Tennesseestorm
I have been using the Lucas and 20w50 for thousands of miles and the engine runs perfectly. I do use one quart of 10w40 with it. If the top end was starving for oil, wouldn't I hear a noise?
markedman90
Slobber! That doesn't sounds very technical, does it?
Nope, but that is actually what it's called. It's especially prevalent @ an idle in cold weather.
AZDude
High mileage oil claims to help reduce consumption by swelling the seals. Something like to that extent. Look up Mobil Super High Mileage Oil.
Dereck
Hi AZDude
When I changed my valve seals they were cracked, with chunks of the sealing lips missing, no amount of seal swelling mechanic in a can is going to work on that.
Regards
Dereck
AZDude
I agree with you Dereck!
TobyU
Hi AZDude
When I changed my valve seals they were cracked, with chunks of the sealing lips missing, no amount of seal swelling mechanic in a can is going to work on that.
Regards
Dereck
I have done many cars that were cracked on the umbrella style and just plain missing on the small o-ring style.
The seal swellers in hm oil and using a heavier weight do slow down drainage down the valve stem....but nothing will make it go away completely...unless you solidify the oil and blow it up.
AC75
So basically, if there's anything that's going to help even just a little, it's gonna be a high mileage synthetic product?
94TownCarSig
So what would you recommend that I do?
227,000 miles. Valve seals have already been replaced. (no smoke)
I do have an oil leak somewhere. Not as bad as before the seals were done. Hard to say where it comes from, lots of old oil caked on the engine.
Any suggestions to get me by until I can afford to have the leak fixed? keep in mind, I don't have extra money to throw around. I've been using 10w-30 usually, the dealer puts in 5w-20 with most oil changes.
Stop leak? Thicker oil? Seal sweller?
fastrace01
To be honest, I would not worry about it. On a car that old, unless you can do the valve steam seals yourself, it just isn't worth the cost to have a head shop go through the head.
It is good on an old engine to have a quart of fresh clean oil poured into it every 500 miles. You can extend your oil change intervals up to 6-7,000 miles.
My old 95 Crown, just under 300,000 miles, and my old blue 95 Town Car- 322,000 miles drank a quart every 300-450 miles. I'd drive the same oil up to 7,000 miles and it was still fairly clean when changed. Of course back then a quart of motorcraft oil was 88¢ at Wal Mart
94TownCarSig
As I said, the valve seals have already been done.
I have a tiny leak somewhere else... oil pan gasket maybe? Or oil filter gasket? Not sure.
gadget73
Have to see where the oil is leaking. Possibly the pan gasket, or the pan, or a lot of other places. Degrease the engine thoroughly and see what gets wet. If its leaking, you'll probably be seeing puddles underneath somewhere. If its not smoking and not leaking, it has to be burning it at speed where you won't so much see the oil smoke.
TCVince
It could be the valve cover gaskets. Mine are leaking, and they have been for a while. I would smell oil once in a while but I couldn't figure out where it was coming from. There's just a little drip in the back that runs down and burns off on the block.
enilsen
It could be the valve cover gaskets.
I agree here. The bolts could have been over tightened when the valve covers were re-installed and caused a small leak or the gasket slipped a bit and is not seated properly.
I put my valve cover gaskets in the freezer before installation so they sat nice and snug in the valve cover gasket groove.
gortiz3
reminds me I need to do my valve cover gaskets...think I might try that freezer trick mentioned
Tennesseestorm
I took the 20w-50 back and got 10w-40.
It worked fine, but I didn't want to take chances.
SignatureSeriesOwner
10W40 is the absolute thickest I would ever run in a 4.6L. Again, despite the engine clearances being larger than when it was new, those oil passages are not. it takes twice the effort to pump 10W40 through the engine than with 5W-20. 20W-50 is a recipe for disaster. If I ever found out someone used something that thick in something other than a diesel, I'd run like hell.
Tennesseestorm
I will tell you one thing... I wish I had of known after all of these years of me changing the oil on this car that I didn't have to remove the under-engine cover to change the oil. :rolleyes: To help speed up the process of the oil change, my dad got under the car and said he would remove the oil filter and drain the oil. I told him that he had to remove that cover first, but I would do it and he said it didn't have to be removed... sure enough, it didn't. I thought for sure years ago that someone told me that cover had to be removed to change the oil. Ugh. My stupidity for not realizing you don't have to. lol.
Dusty
10W40 is the absolute thickest I would ever run in a 4.6L. Again, despite the engine clearances being larger than when it was new, those oil passages are not. it takes twice the effort to pump 10W40 through the engine than with 5W-20. 20W-50 is a recipe for disaster. If I ever found out someone used something that thick in something other than a diesel, I'd run like hell.
I wouldn't run 20w-50 in a modular, but I have run it in plenty of 5.0s in Florida. If I remember correctly it was even in the owners manual for higher temps.
I also run it all the time in my Rotary RX-7. Perfectly acceptable according the the owners manual and plenty of owners.
My GM Marine engine even called for straight 40 weight oil which I though was crazy, but I used it. Very hard to find though.
Just depends on the application.
gadget73
A lot of GM marine engines call for 20w50, 25w40, or SAE40, depending on the particulars. Pretty thick stuff for an engine that normally runs about 160F. I've seen a lot of marine engine failures, but very few were anything lube related, other than cases of not having any or having water in the oil. The only one that comes to mind was a Chris Craft with a stuck choke that the owner ignored for years until the oil was so diluted with gasoline that it wasn't really oil anymore. It completely wiped the rod bearings out and ruined the crankshaft. We didn't pull it down any further, but I don't expect the cam was any better off.
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