BolderS4

Sorry to hijack this forum-- but my friend has a Passat that I changed the oil in today. She told me she usually uses synthetic, but I had it changed with regular.

2002 VW Passat 2.8L V6, no turbo

I have a 2002 VW Passat and usually use Synthetic Oil. I just had it changed with regular oil...is this going to cause problems with my engine?

Do I need to have it re-changed ASAP?

rktskicar

No, will be fine. Oil change interval will be less than synthetic though.

hodan

1. Don't ever ask a question like this again. 2. Next time use what your friend uses.

boston6speed

to synthetic? I was always told that you should not do that but have no physical proof, I am not sure at all if going to regular after synthetic would matter but it seems like it shouldnt. I have also been told that for instance if a car has not had a tranny flush in its entire life (say over six years or 75k + miles) that it shouldnt be done because all the debris from the old tranny fluid that is preserving the seals would be gone and the tranny would be at more risk.

boston6speed

It seems like a valid question. Am I missing something?

Wrinkledpants

Change it at 3k miles. No big deal. It's sad she says synthetic and you put mineral oil in =)

TwentyValveB5+S4

you took it somewhere? or you did it yourself?

either way, sounds like you should have listened to her.

rktskicar

Not sure, but I have been running both and survived.

S4andTLS

new tranny oil can many times save an otherwise ready to fail tranny. If it had that much dirt/gunk in it then it deserves to be rebuilt.

Wrinkledpants

Synthetic does the exact same thing mineral oil does, only better. The carbon chains that makeup synthetic oil are less resistant to breaking down because of the way they are engineering. Think of the carbon chains as long stick like pretzels. If you try to dump a jar of pretzels with a narrower opening upside down, the pretzels won't just drop out like a jar of marbles would. This resistance is what gives oil it's viscosity and is also what keeps the oil between metal parts. So after mineral oil has been run through it's paces, these long carbon chains are shorter from thermal breakdown and shearing forces (literally from the metal parts cutting them down). These shorter carbon strands can move past each other much more easily, and subsequently, move out from between metal parts more easily. This is why synthetics can withstand a longer oil change than mineral oil.

Then there are the added polymers that give oil its multi-weight characteristics. These polymers are coils that contract and expand based on the temperature. When the oil is cold, these polymers are contracted (think squashed spring) and allow the oil to flow more easily. Once the oil heats up, the polymers begin to stretch out and help increase the viscosity of the oil. Both mineral and synthetic oil have polymers added, but synthetic oil is more effective at controlling viscosity. This is how oil can flow so easily at -30 degrees.

Oils also have additives for cleaning, lubricating o-rings, and other tasks one might not think of. Synthetics do this just as good (if not better) than a mineral oil.

Mineral oil has to be refined to remove harmful chemicals before it can be used in motors. This refining can only remove so much. Obviously the more refined oils are more expensive. Synthetics are created from pure ingredients. This means that a lot of the harmful compounds found in mineral oils, are absent from synthetics.

Hope this helps.