Can synthetic oil be cause of leaks?

[Member 10617]

I have posted about unusual oil leaks before, but now I have a therory and want to test it with you.

Before I bought my Bugeye in November 2015, there did not appear to be an unusually high oil consumption problem with the car. Once I got the car, it started leaking oil and now leaks about one ounce per 10 miles!

There is no smoke on starting or while driving, and there is no puddle of oil on my garage floor after a drive, but the oil is leaking out.

Giving this a lot of thought, I have concentrated on the fact that I have been using 20W-50 partial synthetic oil in the car. I don't think the previus owner used synthetic. And I recalled, and confirmed, that synthetic oil can leak or cause old seals to leak.

I am wondering if that is my problem (perhaps? don't know)

I am thinking of draining the engine and putting in a standard dyno oil -- not synthetic -- to see what happens.

My question: what oil would be best to use for this experiment?

 

[SaxMan]

I was once told that synthetic oil has its great properties due to the fact that every molecule is perfect and doesn't "clump" like standard oil. It could be that your leaks are just slight enough that the difference between a perfect molecule and the "clumping" is causing the difference in the consumption.

I use Castrol 20/50 in my '69 Sprite, and since my chassis self-lubrication system plus a little bit of burning is sucking up a quart every 300 miles, it's self changing.

 

[smaceng]

It is my understanding that engines that have been run on dinosaur oil may tend to leak if changed to synthetic. I would change back to dinosaur oil. Why, I do not know.
Scott in CA

 

[59diamond]

I use Valvoline 20/50 racing oil that I get from O'Reily as Scott suggested to me and I have no leaks.

 

[SD Bugeye]

What I was told is they don't cause leaks but any imperfection syn will find and dependent on 'wight' will exit.
the clumping is as close a discription I've heard that discribes the effect.
i used. Zero wight Mobil in a snowblower pulling the starter is like its 80 it's amazing.
did I mention there is sepage at every gasket? Not really a leak just damp.

 

[mightymidget]

As I understand from hear say, synthetc oil will not smoke. So your vehicle could be using oil through combustion and you would not notice. Check your spark plugs for burn color