PAO's and engine seals

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In the last few minutes I have found a seal Company "manufacturer" that has a hand book rating PAO oils"Mobil" and seal compatability.On a 1-4 scale a silicone type seal is the most compatable or might should say will resist better than a neoprene seal rated worst at a 4 level. Problem is the company is closed for the weekend,I will get my hands on that info asap and post the rest of the seals and there rating for PAO's and other Synthetics. This is a complete opposite of what Auto-RX told me on the phone awhile back in that a silicone seal would not take a PAO oil for long. Yehaaa! I am finally getting some answers to some questions I have had since February! [ July 05, 2002, 03:51 PM: Message edited by: dragboat ]
 

MolaKule

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I wasn't going to comment about studies until Dragboat let the cat out of the bag. I too have a study from Toyota Motors and Lubrizol but will withhold comments until your poll has been completed. BTW, what seals are you testing, ACM (Polyacrylic), VMQ (Silicone), or FKM (fluoroelastomers) compounds?
 
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Post away guys, I haven't seen scientific data on seals and materials compatibility in 10 years.
 

dragboat

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MolaKule, Please post away! I am very interested in your findings. I am not doing a study per sey just trying my best to learn more about PAO's and the effects of the various seal material. Just because a company says it is ok to use their oil in my motor,,well I just don't take wooden nickels as I knew all along there MUST be a difference in how certain seals are affected. So I am saying with the seal swell,might not be needed with certain seals and might "over do it" with other types thus ending life early for some seals. Please post you findings! [Smile] [ July 05, 2002, 04:31 PM: Message edited by: dragboat ]
 

MolaKule

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I was referring to Bob's study. Well, this study showed that it was sludge that caused the leakage in most engine seals that sealed against a rotating shaft, such as in journal bearings! Under an SEM (scanning electron microcope), they found that a sludge layer of 0.15 mm had propagated into the elastomer and caused minute splitting of the seal's lip at the seal/journal interface. This tiny split would enlarge over time and allow more leakage. They also found that the stronger additives (I.E., those that contained high levels of Phosphorous and Sulfur, the additives most found in gear lubes) the faster the seal degradation. This leads me to believe that manual transmissions and differential seals are made of pretty good stuff, or that the seals are simply more robust as to design geometry, such as thickness, because it seems that we see fewer seal leaks in those areas. Of course, those components see less heat than do engine seals, too!
 

Al

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My experience has been somewhat different. I must point out it is in the industrial setting. Many seal failures I have seen involve wearing away of shaft material (metal). I really can't say for sure if that is a major factor in auto engines.
 

MolaKule

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You're right Al, I have seen the same situation in refractory gear boxes, which I have attributed to coking of the sludge to a point that the coked residues become nothing more than carbon cutting tools, in effect.
 

dragboat

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Al. Yes it is a factor in some engines. The small block Chevy for example the front timing cover seal will actually cut a groove in the crankshaft over time. When the thrust surface of either the bearing or the crank is worn from many miles especially with the use of a std transmission can cause a leak with a otherwise seemingly good seal at the rear main because of movement. I have seen a few 300k Toyota 20R crankshafts worn beyond repair in relation to the thrust surface on the crankshaft. Dang Dino oil! You would think a motor would last longer than that! [Smile] [ July 06, 2002, 09:46 AM: Message edited by: dragboat ]
 

MolaKule

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Dragboat, It could be that the dino's contained too much seal swell additive such that when sludge and abrasive particles in sludge get between a tight seal and journal, wear results.
 

dragboat

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I copied this from another site,it was refering to the use of synthetics in Asian built M/C's and Cars. "The polyol ester basestock would attack any elastomeric seals" This comes from a guy that I have read many of his posts and I personally respect his seemingly advanced knowledge. So now as I have been since Feb 02 I will continue to try to find out exactly what front and rear main seals the car has. So far I could have gotten closer to launching my own spacecraft as compared to finding out the composision of these seals! [Big Grin]
 

MolaKule

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ACM (Polyacrylic), VMQ (Silicone), or FKM (fluoroelastomers)compounds, per my information to-date, are the only compounds available, unless someone or some company has just developed another compound. Sure, esters by themselves will soften seals, as I have stated before, but PAO's do not soften seals and will allow seals to harden. Esters are added to true synth's to soften seals somewhat to allow them swell and to: 1. increase the oxidative stability of the base fluid, 2. increase high temperature stability, 3. provide a natural detergency to the base oil, 4. provide a high stability Friction modifier, and other qualities previously listed under a different thread.
 
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Originally Posted By: MolaKule
ACM (Polyacrylic), VMQ (Silicone), or FKM (fluoroelastomers)compounds, per my information to-date, are the only compounds available, unless someone or some company has just developed another compound. Sure, esters by themselves will soften seals, as I have stated before, but PAO's do not soften seals and will allow seals to harden. Esters are added to true synth's to soften seals somewhat to allow them swell and to: 1. increase the oxidative stability of the base fluid, 2. increase high temperature stability, 3. provide a natural detergency to the base oil, 4. provide a high stability Friction modifier, and other qualities previously listed under a different thread.
Does anyone think Redline would keep seals in great shape? I'm on a engine seal kick lately.
 
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Originally Posted By: buster
Does anyone think Redline would keep seals in great shape? I'm on a engine seal kick lately.
Pull the motor and replace the seal buster,lol
 
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