Can high mileage oil stop a leak this fast?

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258
I purchased a used Sienna van in July with over 200,000 miles on it. I immediately changed to a 5w-30 Pennzoil Ultra Platinum synthetic for several short OCI to start cleaning out any sludge in the 1MZFE motor. Went from a drop on the ground maybe once a week to several drops a day on the ground using the Pennzoil, so it appears the short OCI and high grade oil flushed something away from the seals that were already capable of leaking when not coated in gunk. First oil change was very dark after 1,000 miles.

On the front of the engine is a long washer/plate that spans two bolts over the exhaust pipe under the valve cover and above the oil filter. It creates a bit of a cupped area where liquids can gather. It was full of pooled oil and clearly leaking onto the exhaust and burning. I could even see the oil sheen from the valve cover gasket downward. I don't like leaking oil, and the rear valve cover gasket is a bear to replace, so I went with a high mileage Pennzoil syn blend 5w-30.

Now, what's strange is that my driving route to and from work is exactly the same. Same oil filter type, etc. After a couple hundred miles, there is no longer any visible sheen of oil leaking from the front valve cover gasket, and the area where it pooled up before at the exhaust is going away and now only about 1/2 as pooled up as it was before the high mileage oil.

Would changing oils make such a quick change? Would it be more likely that I am using a synth blend now instead of full synth? Or is the high mileage additives the more likely culprit?

I'm sort of new to geeking out on engine oils, so pardon if I may be seeing things incorrectly. From my research online, it seems like most people only saw an improvement in oil leakage after several OCI when switching to HMO.
 
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1,967
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USA
Would changing oils make such a quick change? Would it be more likely that I am using a synth blend now instead of full synth? Or is the high mileage additives the more likely culprit?
Highly unlikely and anecdotal that the oil "fixed" or reduced anything on its own.

It is most likely that sludge or other "stuff" has simply plugged the leak for a while.
 
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25,171
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MA, Mittelfranken.de
I purchased a used Sienna van in July with over 200,000 miles on it. I immediately changed to a 5w-30 Pennzoil Ultra Platinum synthetic for several short OCI to start cleaning out any sludge in the 1MZFE motor. Went from a drop on the ground maybe once a week to several drops a day on the ground using the Pennzoil, so it appears the short OCI and high grade oil flushed something away from the seals that were already capable of leaking when not coated in gunk. First oil change was very dark after 1,000 miles.

On the front of the engine is a long washer/plate that spans two bolts over the exhaust pipe under the valve cover and above the oil filter. It creates a bit of a cupped area where liquids can gather. It was full of pooled oil and clearly leaking onto the exhaust and burning. I could even see the oil sheen from the valve cover gasket downward. I don't like leaking oil, and the rear valve cover gasket is a bear to replace, so I went with a high mileage Pennzoil syn blend 5w-30.

Now, what's strange is that my driving route to and from work is exactly the same. Same oil filter type, etc. After a couple hundred miles, there is no longer any visible sheen of oil leaking from the front valve cover gasket, and the area where it pooled up before at the exhaust is going away and now only about 1/2 as pooled up as it was before the high mileage oil.

Would changing oils make such a quick change? Would it be more likely that I am using a synth blend now instead of full synth? Or is the high mileage additives the more likely culprit?

I'm sort of new to geeking out on engine oils, so pardon if I may be seeing things incorrectly. From my research online, it seems like most people only saw an improvement in oil leakage after several OCI when switching to HMO.

With over 200K on it the seals are worn, hardened and may be damaged. Nothing is helping them for very long if at all. There are extremely strong glycol ether and other strong solvents that go under a few brands these not only go after the seal that is leaking but every other seal in the engine.
You can end up in a much worse situation than you are now. Oil is cheap, keep filling it until you either get rid of it or repair it properly.
 

MrPlow

Thread starter
Messages
258
Just a guess, but I think if the oil is leaking slowly, but over a very large surface area, causing oil to collect and drip, then maybe the HM oil might be able to slow it down a bit because no single area of the valve cover gasket is actually super leaky. If my oil drips were from a smaller seal that was leaking the same total volume as the valve cover gasket, then the HM oil can't do enough to close up the gaps?

I've been checking and working on the van weekly since I got it and the oil sheen disappearing under the front valve cover is super obvious.
 
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There is also the possibility that the vehicle was neglected before you got it, your first few oil changes cleared away gunk that was around the seals. The seals were hardened because they had not been in contact with fresh oil for a while, so they leaked until the conditioners in the oil softened them up and now they are doing their job again.
 
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388
Location
USA
With over 200K on it the seals are worn, hardened and may be damaged. Nothing is helping them for very long if at all. There are extremely strong glycol ether and other strong solvents that go under a few brands these not only go after the seal that is leaking but every other seal in the engine.
You can end up in a much worse situation than you are now. Oil is cheap, keep filling it until you either get rid of it or repair it properly.
Are you suggesting that HMs oil will cause leaks?
 
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1,967
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USA
Are you suggesting that HMs oil will cause leaks?
Don't want to speak for Trav but yes they certainly can just as any other chemical introduced into a system can.

It is not uncommon for lip seals to wear and harden into groves and "seal" ( to a point) but when get any additional "softness" back they expand unevenly, crack, chunk out and fail quickly.

There are many "uncommon" circumstances where things happen just like its an incorrect assumption to believe out of the gate that every seal can be "reconditioned" and that somehow a few fractions of a decimal of any number of rubber compounds will somehow restore OEM level performance where it has already physically gone.
 
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USA
Don't want to speak for Trav but yes they certainly can just as any other chemical introduced into a system can.

It is not uncommon for lip seals to wear and harden into groves and "seal" ( to a point) but when get any additional "softness" back they expand unevenly, crack, chunk out and fail quickly.

There are many "uncommon" circumstances where things happen just like its an incorrect assumption to believe out of the gate that every seal can be "reconditioned" and that somehow a few fractions of a decimal of any number of rubber compounds will somehow restore OEM level performance where it has already physically gone.
I certainly wasn't claiming that they could recondition every leaky seal. But if you have a high mileage engine that's not leaking, I don't believe they will cause a leak. That's based on my years of using HM oils in HM mileage vehicles with no leaks. Have some in the family right now.
 
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1,967
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USA
I certainly wasn't claiming that they could recondition every leaky seal. But if you have a high mileage engine that's not leaking, I don't believe they will cause a leak. That's based on my years of using HM oils in HM mileage vehicles with no leaks. Have some in the family right now.

Was not insinuating you were- the difference is I see seal failures with lip seals and have to do failure analysis on them all the time ( especially now with companies tightening up on releases and PSI's on oils and other chemicals).

The bottom line is that when a gasket/seal has reached the mechanical degradation point ( be it weak garter material, embedded contamination, hardness or whatever) and its just randomly found a "sweet spot" where its not leaking ( at the moment)…...

Any change ( regardless of whether its a plus or minus) can be enough to initiate leak.
 

MrPlow

Thread starter
Messages
258
There's no doubt that changing the seals is in good order, but as long as it's not dumping oil all over, and just a drop once in a while, fixing the seals can hold off because of the large amount of work needed for these engines to get to the back half. Might as well wait until the spark plugs need to be changed then replace the valve cover gaskets, then shaft seals when doing the timing belt.
 
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1,464
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There's no doubt that changing the seals is in good order, but as long as it's not dumping oil all over, and just a drop once in a while, fixing the seals can hold off because of the large amount of work needed for these engines to get to the back half. Might as well wait until the spark plugs need to be changed then replace the valve cover gaskets, then shaft seals when doing the timing belt.
Funny you should say that... I recently replaced valve cover gaskets on the Tacoma and decided to check the iridium spark plugs (60k on them) while the coil packs were off. They looked great, did a quick cleaning and gap check and reinstalled. Probably should have cleaned the TB and MAF at the same time but instead I will do those when due. Due-do lol.
 

MrPlow

Thread starter
Messages
258
Correction to the original post. I used Valvoline HM 5w-30 blend. Not sure why I wrote Pennzoil.

Well, I'm now over 1,000 miles on the Valvoline HM 5w-30 and the amount of oil hitting the ground has been significantly reduced to one drop every few days vs a few each day. I still get some oil burning off the exhaust, so the valve cover gasket in the back is still leaking enough for that to happen. But, overall, the HM oil may have remedied the bulk of the issue. I'm going to take the current OCI to 3K and see how it does from there.

Now, was this quick change due to switching back to a synthetic blend vs the PUP FS? Or that the HM oil is a bit higher on the viscosity scale than the PUP? Who knows...

I'm not as "OCD-like" as some others might be about fixing every little thing on an engine so no oil even seeps anywhere. As long as I am not polluting the ground everywhere I park and not losing a dangerous amount of oil that could damage the engine, I couldn't care less about some oil seeping on an engine where some of the seals are a nightmare to fix properly and are best left for when more work needs to be done at the same time.
 
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Three times High Mileage oils have stopped/slowed greatly oil leaks on my vehicles. I put a half quart of leftover Maxlife in a OCI at 20K and it stopped a weepy VC gasket in a couple hundred miles. Yes it can work fast.
 
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