Whats better for seals in the long run?

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1,462
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MD
Synthetics or dino's? Dino's supposedly leave a varnish on seals that can harden and cause them to go brittle. While synthetics on the other hand have a reputation of not leaving varnish but slowly shrinks seals over time.
 
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47,776
Location
Everson WA - Pacific NW USA
I would say the worst things for seals: age heat grit (including gritty bits of coked hydrocarbons) excess crankcase pressure (mostly from dirty breather routes and excess blow-by) The oil you choose can influence these. My money is on synthetic oil.
 
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Location
PA
quote:
Originally posted by moontan: nope. no,no,no,no. the worst thing for seals is a great white shark... [Eek!]
LMAO! [Big Grin]
 
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USA
To date not a single chemist or triboloigists has been able to explain why a synthetic oil would be harder on seals! SO I am still waiting for someone to give me a concrete explanations as to how a synthetic oil is supposed to be so much harder on seals!
 
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1,253
Location
michigan
sorry, i don't know sqat about oil - that's why i'm here. [Off Topic!] punchline of a joke: mechanic - looks like you blew a seal. penguin - no, that's just a little ice cream.
 
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College Dorm...
quote:
Originally posted by Alan: Synthetics or dino's? Dino's supposedly leave a varnish on seals that can harden and cause them to go brittle. While synthetics on the other hand have a reputation of not leaving varnish but slowly shrinks seals over time.
Don't run a mineral PCEO (due to varnish buildup which is #1 cause of seal problems in older engines)...run either a HDEO or a group IV/V PCEO synthetic oil, and your seals will be taken care of.
 

MolaKule

Staff member
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21,883
Location
Iowegia - USA
quote:
To date not a single chemist or triboloigists has been able to explain why a synthetic oil would be harder on seals! SO I am still waiting for someone to give me a concrete explanations as to how a synthetic oil is supposed to be so much harder on seals!
I think a lot of that is old hat stories from the early seventies from uniformed individuals. Today's modern full synthetics have a balance of PAO's, esters, and alkylenes that control seal swell to mimic mineral oils. Now since synthetic oils flow and creep much better than do mineral oils, any seal that is damaged or worn will allow more weeps or drips than mineral oil formulations.
 
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1,539
Location
Shippensburg, PA
quote:
Don't run a mineral PCEO (due to varnish buildup which is #1 cause of seal problems in older engines)
Do you have anything to support this statement? Why would a group II HDEO be better for seals than a group II PCMO? I'm confused... aren't most dino HDEO's just Group II with a more robust additive package?
 
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