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Why some say You can't use synthetic oil after semi synthetic or conventional ! #5247619 10/22/19 10:10 PM
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Cheburashka Offline OP
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Hi ! Why some people say that ..you can't use synthetic oil if you run before semisynhtetic or conventional oil ????
Sound so weird!


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Re: Why some say You can't use synthetic oil after semi synthetic or conventional ! [Re: Cheburashka] #5247626 10/22/19 10:23 PM
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Quattro Pete Offline
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Probably the same reason why some people say that Friday the 13th brings bad luck.


2002 530i   2015 Q5 3.0T   2018 Charger SRT
Re: Why some say You can't use synthetic oil after semi synthetic or conventional ! [Re: Cheburashka] #5247627 10/22/19 10:23 PM
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SirTanon Offline
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It's based off of old experience, old repeated 'knowledge' etc.. it isn't applicable with modern engines and modern oils..

... the only potential cause with modern engines/oils is if the seals have already failed and are just being plugged up by dirt/sludge.. and fresh synthetic oil ends up cleaning said gunk out resulting in leaks.


2013 Nissan Altima SV - 2.5 liter/CVT - 123,000mi
2014 Nissan Altima SL - 2.5 liter/CVT - 69,000mi
2010 Ford Fusion - 274k mi - SOLD
Re: Why some say You can't use synthetic oil after semi synthetic or conventional ! [Re: Cheburashka] #5247628 10/22/19 10:23 PM
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daves87rs Offline
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Nope, I've done it all in one car with no issues.....


2019 Chevrolet Equinox LS
2006 Chevrolet Cobalt LS
Re: Why some say You can't use synthetic oil after semi synthetic or conventional ! [Re: Cheburashka] #5247631 10/22/19 10:27 PM
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FordCapriDriver Online Content
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Just a typical shade tree mechanic myth.


1975 Ford Capri II Ghia 3000 V6 - Repsol Elite Super 20W-50
1988 Ford Escort XR3i Cabrio - Shell Rimula R4X 15W-40 HDEO

Re: Why some say You can't use synthetic oil after semi synthetic or conventional ! [Re: Cheburashka] #5247635 10/22/19 10:33 PM
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userfriendly Offline
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I use group II mono-grades to clean up the gunk synthetics leave behind and to un-stick and clean up the rings and pistons.

Re: Why some say You can't use synthetic oil after semi synthetic or conventional ! [Re: Cheburashka] #5247651 10/22/19 11:28 PM
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ZeeOSix Offline
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"the gunk synthetics leave behind"

Whaaat?

Re: Why some say You can't use synthetic oil after semi synthetic or conventional ! [Re: Cheburashka] #5247652 10/22/19 11:35 PM
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userfriendly Offline
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When are going to change your name to C8?

Re: Why some say You can't use synthetic oil after semi synthetic or conventional ! [Re: ZeeOSix] #5247659 10/23/19 12:02 AM
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SirTanon Offline
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Originally Posted by ZeeOSix
"the gunk synthetics leave behind"

Whaaat?

???


2013 Nissan Altima SV - 2.5 liter/CVT - 123,000mi
2014 Nissan Altima SL - 2.5 liter/CVT - 69,000mi
2010 Ford Fusion - 274k mi - SOLD
Re: Why some say You can't use synthetic oil after semi synthetic or conventional ! [Re: SirTanon] #5247665 10/23/19 12:19 AM
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ZeeOSix Offline
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Originally Posted by SirTanon
Originally Posted by ZeeOSix
"the gunk synthetics leave behind"

Whaaat?

???



Originally Posted by userfriendly
I use group II mono-grades to clean up the gunk synthetics leave behind and to un-stick and clean up the rings and pistons.


Do synthetics "leave gunk behind" ... I doubt it unless you neglect maintenance and never change the oil.

Re: Why some say You can't use synthetic oil after semi synthetic or conventional ! [Re: Cheburashka] #5247668 10/23/19 12:32 AM
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userfriendly Offline
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"What?" is something you say when you cannot hear someone speak.

For clarification, watch the movie Pulp Fiction.

Last edited by userfriendly; 10/23/19 12:35 AM.
Re: Why some say You can't use synthetic oil after semi synthetic or conventional ! [Re: userfriendly] #5247686 10/23/19 01:01 AM
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ZeeOSix Offline
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It means something different when it contains 3 "a"s. grin2

Re: Why some say You can't use synthetic oil after semi synthetic or conventional ! [Re: ZeeOSix] #5247695 10/23/19 02:13 AM
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OilUzer Offline
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Originally Posted by ZeeOSix
It means something different when it contains 3 "a"s. grin2


LOL

Re: Why some say You can't use synthetic oil after semi synthetic or conventional ! [Re: Cheburashka] #5247699 10/23/19 03:18 AM
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userfriendly Offline
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Whaat? Good grief you people are gaga about the word synthetic. Mono-grade lubricant users are compared to global warming deniers and the Flat Earth Society.

Now if you believe in global warming, then why is engine oil going the other way?

Back in the day, 10W30 was the standard multi grade. Truckers wanted thicker and invented the wildcat grade 15W40, likely by mixing 10W30 with SAE 50.

Suddenly 10W30 isn't good enough, because in some climates 5W & 0W cold start protection is need in the winter months. Note; 10W is close to where 5W was 20 years ago.

Not good enough to have seasonal oil changes anymore, cold climates get 5W & 0W year round.

Not good enough that cold climates get 5W & 0W year round, everybody gets it, hot or cold.

This plays right into the need for synthetics and why there are no 15W20 or 10W16 oils on the shelf.

Re: Why some say You can't use synthetic oil after semi synthetic or conventional ! [Re: Cheburashka] #5247712 10/23/19 04:30 AM
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Sayjac Offline
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I think the best explanation of the reason "some people" like EricTheCarGuy might say it was in his conventional vs synthetic youtubes, specifically that part that deals with leaks. He took a lot of heat for his initial yt on conventional vs synthetic oil, so much so he did a follow up. I would say it most applies to much older engines that have run conventional almost exclusively. Synthetic oil doing more cleaning may tend to expose some areas not kept as clean by conventional, and thus leaks become more prominent.


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