How do seal conditioners in HM oils work?

[Mustang_Cougar]

Do the seal conditioners in High Mileage oils cause a permanent change to engine gaskets and seals? Or is this a maintenance situation, meaning that if the use of an High Mileage oil were discontinued, they would "shrink" back to their pre-High Mileage condition?

The reason I ask is that I have a vehicle that has seen a steady diet of High Mileage oil over the last five years; however, I have a huge stash of various dinos that I'd really like to start working on. I would think that the seals in this vehicle are so conditioned with High Mileage additive that it's caused some sort of permanent swelling. Is that off the mark? Or is it something in between (the seals have permanently swelled, but will shrink somewhat without continued High Mileage use)?

Thanks for any insight.

M_C

 

[Alex38]

Excellent question, I've wondered the same thing. Looking forward to this...

 

[Loobed]

I am going to make a guess and say that using conventional 1 or 2 times won't hurt. I do NOT think there is a form of osmosis taking place where the seal conditioners either leach into or out of the seals depending on the amount of concentration of conditioners.

 

[mechtech2]

Some swelling or softening would remain.
Use your dino and note if any leaks occur.
What counts is your car, not what should happen, or has happened to others.

 

[Hokiefyd]

In my experience, the effect that a High Mileage oil has only exists when it's in the engine, and even then, it seems to be only temporarily. My '97 Dakota has a very slight rear main seal leak. Maybe a drop or two after each time I drive it. The only High Mileage oil I've used is Valvoline MaxLife, and it keeps it pretty dry for a while. But after a while, the leak seems to come back. If I use a regular oil, it will leak all the time. If I use a bottle of rear main seal repair, it will stay dry for a while, but eventually return.

I don't the the effect is permanent. Some people don't see the effect anyway. It seems to vary.

 

[JT1]

I soaked three pieces of the same USED gasket(88 merc topaz 2.3 valve cover gasket,silicone rubber) in three different oils. Penn Conv. 5w30,Castrol Synblend10w30,and Valvoline MaxLife 5w30. and let them sit for a month in a dry/room temp. environment.

The penn and castrol had virtually no effect on the gasket(cleaned them a little) but the Valvoline MaxLife blend noticeably SOFTENED the gasket, it was very pliable. I did a blind test with my 14yo nephew and my girlfriend asking each seperatly which piece felt the softest or most pliable and they both agreed that it was piece b(Valvoline MaxLife).

None of the pieces were noticeably swelled.

I would like to think that the gasket would remain pliable for atleast one OCI after changing from high mileage to regualar, but it would be hard to prove.

If your having a leaking or consumption problem why not just stick with a high mileage oil like maxlife. My 91 bonneville with 256k mi ran exceptionally well(zero leaks/.5qt consumption over 3000mi) using maxlife 10w30.

 

[ThirdeYe]

I'm going to run an experiment in my car and my girlfriend's car with MaxLife. Both her car and mine are weeping a little bit. Not enough to drip on the ground but enough to leave the oil pan wet. Mine from the oil pan gasket and hers from the valve cover gasket (I believe). I'm going to run MaxLife for 1-2 OCIs then switch back to regular oils afterwards to see if the weeping comes back after it stops (if it stops). I've used MaxLife in leaking applications before with great success, fully stopping the leaks but unfortunately never got to check if the leaks stopped permanently in them.

 

[Hoosier_Daddy]

Originally Posted By: JT1
I soaked three pieces of the same USED gasket(88 merc topaz 2.3 valve cover gasket,silicone rubber) in three different oils. Penn Conv. 5w30,Castrol Synblend10w30,and Valvoline MaxLife 5w30. and let them sit for a month in a dry/room temp. environment.


you should then soak the maxlife piece in the other oils. i predict no change but that might be different at engine operating temps

 

[JohnBrowning]

Their is a fine line between enough and too much. In a healthy engine keeping the seals clean of deposits and varnish combined with the normal seal swell aggents and amounts in all oils will suffice. THe problem comes from too much oxidation and prolonged use of GI-II+ and very poorly built GIII base stocks. Once you get any varnish,carbon deposits or sludge on the seal it is effectively cut off from all lubricant and will sooner or latter get dry and hard then crack etc......I have never seen varnish build up in oils that are either 100 PAO,DIester,POE or some combo of GIV on up base stocks. Now if you exclude cheap buna gaskets that have no place in a modern engine any ways then synthetics will always produce longer seal life with reguard to modern materals. A clean gasket of seal is a happy seal! One thing I like about POE and DIester's is that they have natural seal swelling properties and do not need anyting added to accomplish this. I have often found that switching to ester based oils like Motuls ALl Ester FOrmula's,Older PEnrite Products,Redline,NEO etc......will often stop weeping seals that are mechanicaly fine just a tad dirty.

 

[bruce381]

most esters used in seal swell or conditioning oils will "soak' into the seal and swell/replace plasticiers lost and soften it the effect will fade as non additized oils are used but will take time kinda puts seal back to new condition

 

[TallPaul]

Originally Posted By: bruce381
most esters used in seal swell or conditioning oils will "soak' into the seal and swell/replace plasticiers lost and soften it the effect will fade as non additized oils are used but will take time kinda puts seal back to new condition
Hey, that gives me an idea. The cords on earbuds harden after a couple months use from either oils in my skin or heat from my body (I tuck the cord inside my shirt collar rather than have it hang loose). So I wonder if I can rub the cord down with esthers or maybe Redline Oil and let it soak for maybe a week to restore the original pliability. The hardened cord is an issue for two reasons: 1) it will sometimes cause the earbud to pop out of my ear, and 2) it will sometimes crack and then the wiring inside goes out.