# Syn vs. traditional oil



## Jay Gallagher (Aug 12, 2010)

Thinking about switching to a synthetic in a 140K mile 1992 VW 2.0. Good idea? Bad idea? Recomendations for brand/weight?


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## tjjoiner (Jul 25, 2012)

I'm also thinking about switching to full synthetic and was told that I may run into leaks as synthetic is thinner than conventional.



bob570 said:


> Synthetic oil cleans much better and is thinner than conventional oil. There could be small cracks in a seal that conventional oil cannot seep through, but synthetic could. Also, if there is any junk in these cracks, synthetic will most likely clean it out, and allow oil to pass through them.
> 
> Some people are able to switch to synthetic on high mileage engines with no problems, others can't.
> 
> Like I said, it's your choice. To be completely honest, as long as you don't beat on it much, you'll probably be fine. That said, I wouldn't go a mile over 3000 miles per oil change on conventional if I were you, and you may want to consider getting the oversize OEM/Mahle/Mann Passat oil filter to allow your engine to hold more oil. You can find them at ecstuning.com. Don't use Fram oil filters or anything you can find at Autozone, they are very cheaply made.


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## shawng (Jul 28, 2007)

Pure BS. synthetic is the same viscosity. That said, if you have a leak that has been plugged with sludge, the increased detergents in the synthetic might clear out the gunk.


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## liquimolyusa (Jul 8, 2012)

*Synt vs conventional*

Your choice. The previous entries are right, both. Synt oil is rich in calcium and other components in the additive package. It is very possible you will have leaks - there are no guarantees that you won't have any leaks - please keep this in mind. I would use a blend - our 10w40 Leichtlauf MOS2. It is a *dark oil* because of the added *Molybdenum Dissulfide* (MOS2).
You will also experience added fuel mileage given the internal friction modification (reduction) operated by the MOS2.
All the best.


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## Jay Gallagher (Aug 12, 2010)

Thanks for the tips. I currently have no external leaks what-so-ever so this change should not present any new problems.

That said, I drive about 2,000 miles a month and getting a little tired of all the oil changes. I always change at 3,000 miles. I have always used Bosch filters and have been running Castrol High Milage 10/40. It's my understanding that this oil may swell some seals. If I switch to syn, will I be creating a new set of problems?


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## gmikel (Nov 10, 2010)

*slipery slope*

there are a million claims and not much to back them up. use what has worked for you.


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## liquimolyusa (Jul 8, 2012)

*Want to use a great 5w40 oil?*

Please take a look at this oil analysis. If you use this oil you could cut your oil changes by at least 50% while maintaining proper lubrication. Synthetic Liqui Moly Oil - Synthoil Premium 5w40.
The proof is in the analysis from an independent oil lab, see the results.
Thanks!

hhttp://forums.vwvortex.com/showthread.php?5863776-Oil-analysis-Liqui-Moly-Synthoil-Premium-5w40


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## Dennis M (Jan 26, 2012)

Jay Gallagher said:


> Thanks for the tips. I currently have no external leaks what-so-ever so this change should not present any new problems.
> 
> That said, I drive about 2,000 miles a month and getting a little tired of all the oil changes. I always change at 3,000 miles. I have always used Bosch filters and have been running Castrol High Milage 10/40. It's my understanding that this oil may swell some seals. If I switch to syn, will I be creating a new set of problems?


You can always try a High Mileage synthetic like Mobil1 High Mileage. It's available in 5W-30, 10W-30, and 10W-40. The 10W-30 and 10W-40 meet ACEA A3 specs.
Another HM synthetic is Valvoline MaxLife Full Synthetic and even their 5W-30 meets ACEA A3. It's hard to find though and I've never seen it in my area. The above mentioned LiquiMoly 10W-40 is probably good too. It's probably the last LiquiMoly oil that still actually uses a lot of moly.

Get a used oil analysis to determine your oil change intervals. You can actually use a pump to take a sample without draining and keep running the oil if the uoa looks ok.


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## 625147 (Jul 14, 2011)

never switch to syn if you have over 70k miles on car and havent used syn.(regurarly) i would warn you of this, as syn has much more detergents in it and can wash up deposits and clog oil passages in motor.
i'd also stay away from 'special' oils like high mileage oils.
unless you engine requires it i wouldnt use weights like 10w 40. use 10w 30 (conv) if you can.


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## tjjoiner (Jul 25, 2012)

air-cooled or diesel said:


> never switch to syn if you have over 70k miles on car and havent used syn.(regurarly) i would warn you of this, as syn has much more detergents in it and can wash up deposits and clog oil passages in motor. i'd also stay away from 'special' oils like high mileage oils. unless you engine requires it i wouldnt use weights like 10w 40. use 10w 30 (conv) if you can.


What would you recommend for cleaning engine sludge and residue? I ask because, while replacing my valve cover gasket, I discovered that my engine has plenty and was thinking of switching over to Valvoline SynTech 5w-30 (it's on the list of approved VW oils) to get it looking like the engine below mine.












1.8Tjettta01 said:


>


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## 625147 (Jul 14, 2011)

no engine flush out with out opening up and flushing engine will do, you may be playing with fire. stick with a good conv oil. 
by opening engine i mean the likes of a complete rebuild, sorry, better sorry now than really sorry later. and all oil passages need to be flushed out too.
use a 10w 30 conv oil or what your car calls for. make sure you use a good filter, i think napa sells good filters (wix).
you need to start using syn while the car is new to make the transition, about 70k miles is max and never use syn unless you clean out block/parts/head, etc.

when opening a motor i like to use kero and a toothbrush, and other cleaning solvents if necessary.


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## Dennis M (Jan 26, 2012)

Go to Bobistheoilguy.com and you'll see in uoa's that conventional oils and synthetic oils have similar amounts of detergents.


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## Jay Gallagher (Aug 12, 2010)

Thank you all for the information. Time to diguest it now.

Jay


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## 625147 (Jul 14, 2011)

Dennis M said:


> Go to Bobistheoilguy.com and you'll see in uoa's that conventional oils and synthetic oils have similar amounts of detergents.


syns are known to clean up deposits that conv oils leave behind, be careful of changing to syn as you can possibly lose an engine.about 70k miles is max for switching to synthetics(new or rebuild). there are more cleaning properties too than conv oils than the detergents alone i think.


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## Jay Gallagher (Aug 12, 2010)

Thanks, I think I'll stick with the conventional oil.


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## BassNotes (Mar 16, 2005)

I think the fearful warnings of switching to synth after 70K or 100K or whatever are overblown.


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## tjjoiner (Jul 25, 2012)

BassNotes said:


> I think the fearful warnings of switching to synth after 70K or 100K or whatever are overblown.


I hope so because I just drained the Castrol GTX the previous owner put in and filled it with Valvoline SynPower (along with a Bosch Distance Plus filter). The odometer reads ~131k right now.


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## vwguy3 (Jul 30, 2002)

BassNotes said:


> I think the fearful warnings of switching to synth after 70K or 100K or whatever are overblown.



Yes I would have to say that too. If your engine is in sound condition and doesn't have any major knocking or ticking I would say it is fine to switch. I got a 01 Jetta from a family member that really didn't take care of it with 187K on it. I put Amsoil euro blend in it and it has been great. I burns a little oil but less then dino oil and sounds better with the 5W/40 oil in it.

When I got the car it was a qt. low and ask my VW mechanic about what he recommended for an engine flush and he to fill up the gas tank and put a qt of transmission fluid in the engine. When the gas tank is empty change the oil and put syn. in it. Haven't looked back since!!!!

Thanks
Justin


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## VWMech01 (Apr 13, 2005)

tjjoiner said:


> What would you recommend for cleaning engine sludge and residue? I ask because, while replacing my valve cover gasket, I discovered that my engine has plenty and was thinking of switching over to Valvoline SynTech 5w-30 (it's on the list of approved VW oils) to get it looking like the engine below mine.












Yours looks great! And the one below looks IMMACULATE! 

Now MINE...mine is sludgy! Wish I had a pic! 

As for changing: All concerns are valid: swelled/shrinking seals, sludge depositing in smaller openings (namely PCV and vacuum lines), and are valid at just about any mileage depending on MANY factors: quality of oil up to that point, # of short drives, climate, driving habits, et. al. There's no universal answer. 

What you should know is that the synth will loosen sludge and flow it around anywhere the oil goes. The majority should be caught in the filter or on the oil pickup tube screen. The finer stuff will collect in lower flow and lower pressure areas, i.e. smaller passages. Only knowing the amount of sludge will tell you if this will be a problem or not. 

At least 1, possibly 2 dealerships have said specifically NOT to put synth into a 2.0. I don't understand how it could be such a problem to warrant their semi-stern warning. It's not going to become a garden sprinkler or anything... 

But at the same time, not all rubbers (read: seals) are compatible with sythetic oil. I don't know that chemistry, but I can guess that the synth molecule isn't exactly a relative of the rubber molecules of the seals in a 2.0. Perhaps newer engines have more silicone in the seals than rubber? I'm just thinking out loud...


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## Cabriodog (Jun 24, 2011)

*98 Jetta ABA with 292,000*

I hope this all isn't true as I switched a sealed tight ABA with almost 300K on it to an all synthetic castrol because Advance had a deal I couldn't pass up. IDk I have 2k on the oil change and I run the heck out of it.


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## Dennis M (Jan 26, 2012)

VWMech01 said:


> But at the same time, not all rubbers (read: seals) are compatible with sythetic oil. I don't know that chemistry, but I can guess that the synth molecule isn't exactly a relative of the rubber molecules of the seals in a 2.0. Perhaps newer engines have more silicone in the seals than rubber? I'm just thinking out loud...


This may have been partially true many years ago, but oils and testing requirements are always evolving.

http://www.castrol.com/castrol/genericarticle.do?categoryId=9014502&contentId=7017050

FACT or MYTH?
Synthetic motor oil will ruin the seals in older vehicles and cause leaks.
Answer: MYTH! We're not sure who leaked that rumor, but synthetic motor oil does not cause leaks. It is 100% compatible with all automotive seal and gasket materials. In fact, SYNTEC meets additional ACEA seal protection requirements not even addressed in API specs. 

Those requirements from:
http://www.acea.be/images/uploads/files/2012_ACEA_Oil_Sequences.pdf

1.10 * Oil / elastomer compatibility CEC L-039-96 
Max. variation of characteristics after immersion for 7 days in fresh oil without pre-ageing
Hardness DIDC
Tensile strength
Elongation at rupture
Volume variation

http://www.swri.org/4org/d08/global/oilelstm/

http://www.cectests.org/settestdoc2.asp?subdoc_id=11223


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## 08Rabbit1 (Jun 30, 2008)

Dennis M said:


> FACT or MYTH?
> Synthetic motor oil will ruin the seals in older vehicles and cause leaks.
> Answer: MYTH! We're not sure who leaked that rumor, but synthetic motor oil does not cause leaks.


I've had synthetic oil start leaks, and to see those leaks disappear upon returning to conventional oil. Even Mercedes Benz North America has conceded that synthetic oil is more prone to leak, and to cause existing leaks to get worse. That synthetic oil is NOT more prone to leak is the myth, which is not to say that it always causes leaks.


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## BassNotes (Mar 16, 2005)

08Rabbit1 said:


> I've had synthetic oil start leaks, and to see those leaks disappear upon returning to conventional oil. Even Mercedes Benz North America has conceded that synthetic oil is more prone to leak, and to cause existing leaks to get worse. That synthetic oil is NOT more prone to leak is the myth, which is not to say that it always causes leaks.


I've had leaks develop with conventional oils too (though not in the past twenty-plus years that I've used only synth).


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## VWMech01 (Apr 13, 2005)

08Rabbit1 said:


> I've had synthetic oil start leaks, and to see those leaks disappear upon returning to conventional oil. Even Mercedes Benz North America has conceded that synthetic oil is more prone to leak, and to cause existing leaks to get worse. That synthetic oil is NOT more prone to leak is the myth, which is not to say that it always causes leaks.


This ^

And some supplementary reading:

http://www.bobistheoilguy.com/


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## TooSlick (Feb 17, 2000)

A 5w-40, HD gas and Diesel engine oil will slowly clean out those deposits. The Mobil 1, Turbo Diesel Truck or the Rotella T6 synthetic are both decent oils that are easy to find and work well in this engine.

Synthetic oils must pass the same tests for compatibility, with the various types of elastomeric seals and gaskets used in modern engines. You can change to synthetic at any time in any well maintained gas or Diesel engine.

TS


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## tdot3570 (Nov 13, 2011)

*ive switched to synthetic in two vw mk3s with higher mileage with no bad effects*

I switched a 1993 1.8 golf cl to synthetic at 350,000 kms and my current 1996 golf to synthetic at 250,000 kms with no ill effects.Its going to depend on the car of the engine and car itself.The 1.8 had leaky valve seals but I wanted to extend the life of the car as best I could.I bought it used and abused.I drove it for two years like that with no issue with the oil but did have the valve seals replaced.The 2.0 I decided to switch over and have been driving like that for almost a year now.I guess alot will depend on how you maintain and repair the car.I went from Mobil 1 to Lubri Moly.I think more people need to pay attention to the coolant they put in their vws than the oil!!!


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