Will Synthetic Motor Oil Cause Engine Seal Leaks? Let's find out!

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  • Published on:  Monday, October 7, 2019
  • Conventional Shell Rotella T4 15W-40 compared to Full Synthetic T6 5W-40 for causing engine seal leaks in a 45 year-old Ford 5000 tractor. I bought the oil used in this video and do not have any sponsors. Thank you very much for supporting the channel by watching the commercials and through Patreon support. https://www.patreon.com/projectfarm

    Merch: https://teespring.com/nl/stores/project-farm

    This video is only for entertainment purposes. If you rely on the information portrayed in this video, you assume the responsibility for the results. Project Farm LLC
  • Source: https://youtu.be/Pa4RwsiZUmI


  • Jimmy Barr

    Jimmy Barr

     30 minutes ago

    Man, I’ve always appreciated this channel for the large amount of unbiased detailed information. But after watching this, there is even MORE detailed information and facts that I have never considered. Project Farm has been and always will be the most awesome YouTube channels out there. Thank you.

  • awesomeferret


     2 hours ago

    I've never heard this, I've always been told the exact opposite, that synthetic oil is better for engines in every way and traditional oil is just a legacy budget alternative. Is this myth really that prevalent?

  • Paul Straney

    Paul Straney

     3 hours ago

    Wow, I haven't heard this talked about for some time now. There is only one reason a leak at a seal will occur after changing over to synthetic oil - the seal itself. If the seal that is leaking is removed and replaced properly, the problem will go away. Looking at the seal lip under a microscope (if needed), it will be cracked. A quality synthetic oil, such as Amsoil and others, use high quality detergents and additives. The cleaning action from new detergents will aid in cleaning the seal, allowing the cracks to pass more oil than before the change over. There is no "miracle in a can" that will rejuvenate a leaking seal. Synthetic oils have to be compatible with all manufacturers engine seals, the majority are currently Buna-N. Synthetics are also compatible with Viton. Bottom line - NO, synthetics will not cause engine oil seal leaks.

    On the subject of seals, Teflon seals are now being used. They are designed to be installed totally dry. The action between the seal and the rotating surface (crankshaft) will cause the seal to "bed in". If oil is applied to a Teflon seal, this will not occur and it will leak forever.

  • Stephen Smith

    Stephen Smith

     3 hours ago

    Who do you use for testing your oil? Looking to test oil off my Jeep. Thank you.

  • Richard Evans

    Richard Evans

     5 hours ago

    I know this may seem like dumb question but what exactly is synthetic oil in comparison to mineral I know it’s man made but what advantages if any are there for the mechanically inept like me thank you 👍🏻

  • Richard Evans

    Richard Evans

     5 hours ago

    This man is more than a public service he’s a world service and I’m mighty grateful for it too 👍🏻

  • Marlon Octavianus

    Marlon Octavianus

     11 hours ago

    I've been using synthetic oil for 5 years on my 23+ year old engine and nothing leaks.. And, i'm using Pertamina Fastron Techno 10w-40.. You should try it..

  • Todd Sauve

    Todd Sauve

     14 hours ago

    Thank you for doing all this testing for us. This is very useful information to have and should significantly lengthen the life of the vehicles for people who put it into practise!

  • Greg Olson

    Greg Olson

     17 hours ago

    Synthetic oil will cause seal leaks in an old sears hydrostatic tractor as in SS15. I have had 2 of my garden tractor club members state so. I beleive they were designed to use non detergent oil.

  • Thomas Sipes

    Thomas Sipes

     18 hours ago

    synthetic oil does not cause leaks. after my time in the automotive industry, any time that we had the ol' leaky valve cover, even on my own cars, and had a chance to peer in, these engines had already cause accumulations of sludge present from poor/lesser maintenance. failed main seals are their own other special beast as they may have different rotary disc liquid deflectors, the best samples for X oil causing the engine to leak would be the valve cover gasket. the synthetic oils typically tend to have better detergent packages which work well to clear away sludge/carbon/junk deposits. the synth is actually cleaning the damage away, that was pre-existing.
    the un-knowing average autozone/ORLY customer that does their own oil change because it's cheaper typically has this happen because they may have had a cheaper maintenance care for the vehicle, or had gaskets that were old and seeping anywho. with the switch to the better stuff that might have been on a sale, or recommendation of a well intending clerk to sell the synthetic, the end-user only sees that now they have to get a new repair performed. sure, the leak was kind-of caused by the synthetic, however it was the other "dino" oil that simply had junk blockin' up all the gaps in the current existing gasket.

  • J LT

    J LT

     18 hours ago

    When do we get to see the carbon build up in your lungs lol.

  • Francesca Calderoni

    Francesca Calderoni

     19 hours ago

    I'm a huge follower of his channel. My spouse works at AutoZone, and I always recommend they watch his stuff before risking lying/assuming to someone. A lot of know how in these.

  • AJ


     20 hours ago

    I have never seen any leaks with the T6 oil in my 3 Kubotas skid loader, lawn mower, and utility vehicle and never a leak in any of them

  • James Avery

    James Avery

     22 hours ago

    Can you test which beer gives you the worst hangover ?

  • Draxindustries1



    To make that engine work harder if it had been fitted with a plough the turbo would have spooled up to the max..

  • Gianni Ludovico

    Gianni Ludovico


    Shell Rotella T6 smells like peppermint

  • cesarzuniga1



    That makes sense now. I have a 1998 mercedes c230. I have always used oil from the dealer and for some reason I decided to go with 5-40 Castrol Edge Full Synthetic oil and I just replaced the valve cover gasket and the oil pan gasket. Prior to this I had never noticed any oil around the engine. Definitely true that they leak.

  • twowheelflyercr



    A common concern with motorcycles with a wet clutch is that a full synth oil will cause the clutch to slip

  • kraljo1



    Had two old (1987. and 1993.) VW develop leaking oil everywhere after switching to synthetic oil,but in the long run. One day you lift the hood and ask yourself WTF? Some oil additives took care of that and mineral 15w-40 is king after that.

  • fakebrake



    Bought a 2009 f150 with 104000 miles five years ago. Has been on full synthetic for the last 3 oil changes. Zero leaks.