Leaking because of Synthetic oil

[KL31]

Okay, so my friend has synthetic fear and thinks his engine will definitely leak oil if he uses it. My opinion is if the oil has similar specs and KV40/100 HTHS etc then why would synthetic leak vs syn blend? He had leaks a while back (blamed valve covers + synthetic) and has no real leakage now.

His engine is rebuilt but recently supercharged. I think full synthetic such as Castrol Edge 5W40 will serve him well for a S/C engine. He is using mineral and sometimes semi synthetic.

Specs of current oil are:

10W40 -
KV40 14.37
KV100 96.31

Edge:
KV40 84
KV100 14

Are his fears warranted? Does full syn actually leak better past valve cover gaskets, oil pans etc? Need the BITOG mythbuster team.

 

[Olas]

Bad gaskets cause leaks. If you use mineral, blend, or full syn it will leak past a bad gasket.
If the engine is sealed properly it WILL NOT leak, regardless of fluid.

Remember, if your friend has an irrational fear all the data in the world won't sway his opinion, let him get his warm and fuzzies by following his superstition.

 

[demarpaint]

Originally Posted By: Olas
Bad gaskets cause leaks. If you use mineral, blend, or full syn it will leak past a bad gasket.
If the engine is sealed properly it WILL NOT leak, regardless of fluid.

Remember, if your friend has an irrational fear all the data in the world won't sway his opinion, let him get his warm and fuzzies by following his superstition.


Well said.

 

[tomcat27]

Ditto what the others have said. I highly doubt that his engine will leak due to the use of synthetic oil. Besides, most "synthetics" are using (highly processed) mineral base stocks and also likely contain seal swell and seal conditioning agents. back in 1998 I could repeatedly demonstrate a rear main seal leak in my 98 Ram by using Amsoil. Switching to M1 stopped the leak. after a few switches back and forth between Amsoil and M1, I determined that I would not run Amsoil in my Ram. A friend had a similar situation with her Jeep (brand new) and her dealer happily replaced the rear seal - no more leak with Amsoil.

Besides those two events, I have never witnessed any leaks from synthetics - only benefits.

 

[mr_blackstock]

G'day,

I had a bike with a high mileage engine, around 240K. I went over to synthetic, same weight as the mineral I was using. The engine developed a small weeping leak from an O ring between the head and block. I went back to mineral and the issue stopped after awhile. I spoke with a work mate who was an engineer and he suggested that with mineral oil, depending on engine useage etc, some seals can accumulate "gunk", and even in small amounts, this gunk can sometimes create a semi seal that can remain in place for ages. Apparently, by me changing to synthetic, with potentially a high amount of detergents, the oil washed away the gunk seal from the O ring, hence the leak.

later I changed the engine over to another engine, same type exactly, just much less mileage, and ran that on synthetic without issue. So, the reasoning about mineral oil tarnish or gunk or buildup being displaced by an oil high in detergent may ring true. Yet, if synth oil can swell seals, why not mine?

just a thought.

 

[cmhj]

end of the world

 

[ebr1190rx]

Back in the 80s when a friend had a Datsun B 210 he switched it to Mobil 1 oil it's I guess it was probably a 20 weight and it started to leak and eventually all that leaked out so back then yes since they did cause it to leak for
whatever reason he put conventional back into it and it runs fine or anyway for the next 20 years lost track of him after that it was still going. But my Jeep GC 5.2 and many of my other vehicles that I put oil in started out on conventional and then went synthetic and had no problems whatsoever with any leaking

 

[wemay]

Directly? No
Indirectly? Yes

On a high mileage dirty engine that has used dino all it's life with careless oci, the introduction of syn may expose a leak already there but gunked over by deposits or sludge until the syn cleans it away. If the engine has had proper maintenance, no issue should arise.

 

[FZ1]

Sure it can leak. Sometimes better flow and more detergents is not a good thing.

 

[Nickdfresh]

Originally Posted By: Olas
Bad gaskets cause leaks. If you use mineral, blend, or full syn it will leak past a bad gasket.
If the engine is sealed properly it WILL NOT leak, regardless of fluid.

Remember, if your friend has an irrational fear all the data in the world won't sway his opinion, let him get his warm and fuzzies by following his superstition.


This. In fact a quality syn containing a dose of esters will mitigate leaks on gaskets...

 

[SatinSilver]

I recently switched the 05 Matrix over to a High Mileage Full Synthetic, Valvoline which is even better with a $10 rebate and price matching with Walmart. About $8.50 for a 5 qt jug.

 

[Johnny2Bad]

He's wrong, but life is too short to convince the dim the folly of their ways. Let him buy dino oil and move on.

 

[BrocLuno]

Look, we all can claim no leaks, etc. He may not believe a word of it. It's his motor.

If he has used a syn-blend in the past, maybe that's as good as it'll get with this person. Dino oils have worked for over 100 years. Premium dino oils have been used in blown motors since the 1950's at least. They don't die because they don't get synthetic. They die because they get beat on, get into detonation, or go lean ...

Talk him into a premium oil known to hold up in blown motors. VR-1 Silver Bottle comes to mind. Joe Gibbs Driven is another. Kendall makes some really good dino oils. These are well proven and well understood.

Just make sure the package is solid. Hopefully all the by-pass's are blocked off. He's running an oversized hydraulic filter (no internal by-pass). He has a magnetic drain plug (so he can see if it's shedding metal). And he changes his oil at say 3~5K.

It'll be OK. Synthetics are not for everybody ...

 

[mazdamonky]

If the Synthetic causes leaks in his valve cover gasket or oil pan gasket or anything similar, then they needed replaced anyways.

 

[LeakySeals]

Modern synthetic (hydrocracked dino) oil flows better. Creeps better. Thinner. Cleans better. So it can creep into and flow out of a bad seal easier than conventional. But there was some truth to the claim years ago.. Back when the word synthetic meant non-petroleum based oil. That stuff was good for engines, "bad" for the seals at the time.

 

[WylieCoyote]

It would be hard to prove oil vs. coincidence. This happened to me with my '78 Monza that spent its early years with rarely-changed PYB in the pan. I switched it over to Castrol GTX, an allegedly high-detergent oil, when I bought it in 1986, and about 6 months later the rear main began dripping on my driveway.

Detergents in the oil, or was it already in the cards? I think it would take a team of forensic scientists to prove either way.