Seal Swelling vs. Seal Conditioning

brad_d · Aug 2, 2004

My first attempt to post this question seems to have simply disappeared. Here goes again:

Is "seal conditioning" simply a euphemism for "seal swelling", or does it mean something else/more? I'm thinking of high-mileage oils, but I suppose this could have broader scope.

There seem to be some on these boards who use the terms interchangeably, although it's possible my perceptions of this are in error.

TallPaul · Aug 2, 2004

quote:

Originally posted by brad_d:
Is "seal conditioning" simply a euphemism for "seal swelling", or does it mean something else/more? I'm thinking of high-mileage oils, but I suppose this could have broader scope.

It seems like a knee-jerk response of the anti-high mileage oil crowd to say they use seal sweller and will ultimately cause leaks. I believe seal conditioning is the proper term and ideally that involves cleaning off the seals and restoring their original pliability.

So then I wonder what, in a new engine, is the best way to keep seals in good shape and what, in an old engine, is the best way to restore old seals?

MAJA · Aug 2, 2004

I work in the rubber elastomer sealing business, and when I hear seal swelling, I think of a seal that is being compromised, or degraded, and will be failing shortly. In the short run, it may be stopping a leak, as it is filling in a greater area. A torn seal or a worn sealing surface will be fixed temporarily. But the seal will need replacing eventually, and the sealing surface checked for wear. I think it would be unusual for a seal to be exposed to anything in or on an engine to cause it to swell, or degrade, but of course anything can happen.

As far as seal conditioning, as has been mentioned with doing an Auto-RX treatment, there is no swelling. Instead, the sludge creating a false seal is cleaned/removed, exposing the actual seal to to the conditioning elements of the oil. It is no longer "drying out", and hardening, from lack of oil. Seals need lubrication as much as bearings. The seal then is able to reconform by returning back to its original softness/hardness. This is a durometer measurement. Now, if the false sludge seal is covering a tear or a damaged or brittle seal, obviously there would be a leak problem.

One of the side benefits of some of the products mentioned on this board, in their maintenance doses, is to allow a seal to conform or stay conformed, in additional to keeping things clean.

brad_d · Aug 3, 2004

Thanks very much, guys. Very informative.

thedawk · Aug 3, 2004

So correct me if I am wrong, but PAO oils do not condition the seals enough and cause them to dry out and become brittle. However, certain kinds of esters are added to replentish the dried out seals and keep them soft. Redline already has a lot of these esters in it so it does not have these as additives. Am I on the right track here?

thedawk

MolaKule · Aug 3, 2004

Check out this Tech Brief:

http://theoildrop.server101.com/cgi/ultimatebb.cgi?ubb=get_topic&f=21&t=000058&p=2#000044

MolaKule · Aug 3, 2004

quote:

So correct me if I am wrong, but PAO oils do not condition the seals enough and cause them to dry out and become brittle. However, certain kinds of esters are added to replentish the dried out seals and keep them soft. Redline already has a lot of these esters in it so it does not have these as additives. Am I on the right track here?

thedawk

Any seal immersed in a fluid such as Motor Oil will NOT DRY out. This statement goes against logic.

PAO's do cause some seal swell (no conditioning) but not as much as mineral oils. Special esters are usually added to mineral oils and blends to enhance seal swell. If the full synthetic fluid contains esters or di-esters as part of the formulation, then extra seal swell agents need not be added.

[ August 03, 2004, 02:55 PM: Message edited by: MolaKule ]

Ray H · Aug 3, 2004

According to Exxon/Mobil (and I believe they're in a position to understand the chemistry as well as anyone...), PAOs traditionally did NOT cause seal swelling as conventional base stocks do. Consequently, the first attempts at commercial use of PAOs for synthetic automobile engine oil had a tendency to leak like a sieve past the mains' seals. Some smart guy came up with the idea to add a synthetic ester that would promote controlled swelling of the elastomeric seals to solve the problem. According to other posts on this forum, Mobil 1 SS may be using other chemistry to achieve that, now.

glxpassat · Aug 3, 2004

So do excellent oils like Delvac 1300 and Delo 400 swell the seals or will they keep them in good condition over years of use? Would a maintance AutoRX be required to do this?

Jelly · Aug 3, 2004

quote:

Originally posted by TallPaul:
So then I wonder what, in a new engine, is the best way to keep seals in good shape and what, in an old engine, is the best way to restore old seals?

New Engine - Use synthetics or HDEO's to keep seals in good condition.

Old Engine - Start off with an HDEO and see if seals are in good enough shape to once again be used with "regular" synthetic or mineral oil.

In my particular case, they weren't, so I'm now trying a HM oil to see if that will help my seal issues...

Jelly · Aug 3, 2004

http://www.pzlqs.com/Tech/Pdsheet/DomesticMarketing/EngineOils/Pdf/HighMileageVehicle.pdf

"Seal Conditioning"

http://www.valvoline.com/pages/products/product_detail.asp?product=7

"Condition Seals"

http://quakerstate.com/pages/products/oil_highermileage.asp

"Seal Conditioning"

http://www.havoline.com/products/na/motoroil_hhm.html

"Seal - Conditioning"

etc, etc, etc...

Ross · Aug 3, 2004

What about an old car with few miles?

I recently bought a 88 pontiac with a 2.8 v-6

The car only had 11,000 miles on it and sat for long periods of time without running. I ran 1500 miles of auto rx thu it (the carrier oil was M1 10w30). I am 300 miles into the first rinse phase (chevron dino 5w30). I have a rear main seal oil leak. After the car sits for about 5 days without running it will drip 4 drops. I removed the bell housing dust shield to verify that it was the main seal and not the oil pan gasket or distr. O ring.

If I drive the car more often then every 5 days, I do not see any dripping.

So I plan on 2000 miles on this rinse phase, if the leak does not stop I will do another auto-rx cycle.

Should I stay with dino and maintenance auto rx on the low mileage low engine or can I use my favorite oil M1 ??

Was my main rear oil seal just dryed out from not using it??

THANKS! This has been a very informative thread.

Ross

Seal Swelling vs. Seal Conditioning

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