Is switching from synthetic truly murderous on an engine

[00NissanNinja]

I've heard people say it. Is it really all that true, that I do not know. I'm thinking about putting high mileage oil back in my car (this is not dealing with bikes but this question can apply for bikes as well), simply because my car is old and I feel as though the synthetics caused me to have some leakages of oils from the old seals on my car (praying its not the head gasket).

[scotty]

I find on old cars you should use reg oil. The older seals seems like they can't handle the syn oils. Unless you started running it early in its life. I have heard that syn oils could shrink seals.?. Not sure if that is true or not. Most my cars are as old as me, so I run reg oil in it.

[00NissanNinja]

Yeah thats what I heard so I'm definitely going back to regular oil. From my experience it seems that statement may be true. Its just that some people say its worse to go from synthetic back to regular.

[kkim]

Is switching from synthetic truly murderous on an engine ?

no

[rockNroll]

Except for kkim's post, everything in this thread is pretty much false. Synthetic won't cause leaks. It's fine to switch to non synthetic. The cow did, in fact, jump over the moon.

[warlord]

Switching from regular to synthetic can worsen leaks depending on the condition of the seals, especially with a high mileage car. Regular oils can hide the fact that your seals are bad because the the sludge reinforces the leaky seal. Switching to a synthetic (which does a good job of removing that gunk) can then cause leaks to reveal themselves.

Once you have leaks then switching back to regular oil, even high mileage oils with seal conditioners, isn't likely to help. You'll need to go through your engine to find the leaks and replace the leaky seals.

Bottom line: synthetic oil didn't cause your seals to leak rather the sludge from using regular oil in your engine was hiding the fact that your seals were bad.

[kkim]

Originally Posted by warlord

Switching from regular to synthetic can worsen leaks depending on the condition of the seals, especially with a high mileage car. Regular oils can hide the fact that your seals are bad because the the sludge reinforces the leaky seal. Switching to a synthetic (which does a good job of removing that gunk) can then cause leaks to reveal themselves.

Once you have leaks then switching back to regular oil, even high mileage oils with seal conditioners, isn't likely to help. You'll need to go through your engine to find the leaks and replace the leaky seals.

Bottom line: synthetic oil didn't cause your seals to leak rather the sludge from using regular oil in your engine was hiding the fact that your seals were bad.

that is my understanding as well.

[Boom King]

Originally Posted by scotty

I have heard that syn oils could shrink seals.?. Not sure if that is true or not.

I think this might have been a problem when synthetics were first produced for consumer automotive use decades ago. The belief was that certain PAO based synthetics would cause plastic car parts made of Polyoxymethylene to become brittle and crack, etc. Not sure if this was ever true or not. Could have been a myth started by rival oil companies for all we know.

I don't use synthetic so I admit I don't follow this debate closely and for the OP I'd be surprised if your leaks were indeed caused by using synthetic oil given modern car manufacturing and modern oil formulations. However, if it makes you feel better, switching to dino oil should be fine as well.

[00NissanNinja]

Originally Posted by warlord

Switching from regular to synthetic can worsen leaks depending on the condition of the seals, especially with a high mileage car. Regular oils can hide the fact that your seals are bad because the the sludge reinforces the leaky seal. Switching to a synthetic (which does a good job of removing that gunk) can then cause leaks to reveal themselves.

Once you have leaks then switching back to regular oil, even high mileage oils with seal conditioners, isn't likely to help. You'll need to go through your engine to find the leaks and replace the leaky seals.

Bottom line: synthetic oil didn't cause your seals to leak rather the sludge from using regular oil in your engine was hiding the fact that your seals were bad.

Yeah I know that. It is just I was talking to this mechanic and he was really adament about it. I felt like that switching it wouldn't do much of anything (and still feel that way). Just curious what most people think. I actually think its just my distributor leaking oil from its seal and seeping everywhere else. Its a very small seepage of oil. Mainly I want to see if someone had some facts to back up the claim/myth its bad to switch from synthetic to regular oil.

[dubojr1]

Originally Posted by warlord

Switching from regular to synthetic can worsen leaks depending on the condition of the seals, especially with a high mileage car. Regular oils can hide the fact that your seals are bad because the the sludge reinforces the leaky seal. Switching to a synthetic (which does a good job of removing that gunk) can then cause leaks to reveal themselves.

Once you have leaks then switching back to regular oil, even high mileage oils with seal conditioners, isn't likely to help. You'll need to go through your engine to find the leaks and replace the leaky seals.

Bottom line: synthetic oil didn't cause your seals to leak rather the sludge from using regular oil in your engine was hiding the fact that your seals were bad.

[wvninja]

Originally Posted by 00NissanNinja

Yeah I know that. It is just I was talking to this mechanic and he was really adament about it. I felt like that switching it wouldn't do much of anything (and still feel that way). Just curious what most people think. I actually think its just my distributor leaking oil from its seal and seeping everywhere else. Its a very small seepage of oil. Mainly I want to see if someone had some facts to back up the claim/myth its bad to switch from synthetic to regular oil.

Mechanics get set in their ways.

A crazy man can call the sky purple, believe that its purple and assure everyone around them that it's purple. Doesn't mean its true or based around any facts

[dubojr1]

Originally Posted by wvninja

Mechanics get set in their ways.

A crazy man can call the sky purple, believe that its purple and assure everyone around them that it's purple. Doesn't mean its true or based around any facts

Sounds more like a mechanic that was looking for an easy way out of a problem he could not explain. Just blame it on the synthetic...

Personally I'd consider other mechanics.

[Flashmonkey]

Originally Posted by rockNroll

Except for kkim's post, everything in this thread is pretty much false. Synthetic won't cause leaks. It's fine to switch to non synthetic. The cow did, in fact, jump over the moon.

LOL...winning.

But ya, if you're talking about your bike, switching to syn shouldn't be too much of a problem.

[gfloyd2002]

There is a good reason for OPs question, but that is with old synthetics. New synthetics are fine.

Echoing earlier posts in this thread, early synthetics got a bad reputation for leaking. This was because the seal-swell characteristics of the new synthetics were different from those of the mineral oils they replaced. If the seal-swell rate was lower, the seals shrank and oil leaked from crankshaft seals and rocker cover seals. If the rate was higher, the seals swelled a little extra and the engine was tight. Then if the owner changed back to mineral oil, or added a quart when no synthetic was to be had, things got really bad. The crank seals had become worn, in their turgid state, and then relaxed. The valve cover seals were compressed when swelled, and when the different oil was added, everything leaked.

However, synthetics on the market now have resolved this. You should have no problem switching back and forth.

[00NissanNinja]

Yeah cool, thats what I figured. Seems its my dizzy leaking from what I can see now that I have torn some crap from around it. Its seeping oil along the front of my engine. Guess I'll be fixing that when I get to it. I do all maintenance on my car, just don't want to f it up. I've already fixed so much lol. Thanks for the reassurance

[wvninja]

kkim is "winning the internet"

[trex]

please go to bobistheoilguy.com for all of your oil needs

this page in particular deals with mineral vs. synthetic
http://www.bobistheoilguy.com/cms/in...=article&id=81