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alright Iv'e been running Mobil synthetic motor oil since the frist oil change and I was just wondering if I could swich my oil to standerd mobil oil? I had big plans for my car but never got around to them so I don't see why I need to run synthetic motor oil anymore.

 
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You can. Its not great for the engine though. The seals have soaked up the synthetic oil. The best way to go about it woud be to drain your system, replace all of the seals / gaskets and then run regular oil. Or slowly move to regular oil over the next couple of changes. Replace the synthetic with semi synth for a couple of oil changes, and then go to regular oil.

 
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or just drain it out and put regular oil in it.

 
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If you do that, you will kill your seals / gaskets life big time. And it will probably start to leak oil.

 
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Stinky,

I keep hearing over and over that syn oils will kill seals. Can I ask how you know this to be a fact? I'm not slamming but I am curious about the factual basis for that statement.

Years ago and I mean many years ago, Mobil 1 had a seal problem based on the chemistry but they quickly changed the forumula. This was about 25 years ago and not last week. Despite this being very ancient history, the myth still persists.

Syn doesn't cause a seal to leak. If that were true then No would already have leaks. He didn't say he had any.

I've been running syn oil in my Explorer for 140k miles and there have never been any drips or drops other than what I spilled. It's a horribly incorrect myth that syn will cause leaks or ruin seals if you use oil from a reputable manufucaturer.

No - I suggest that you run M1 0W-20 unless you're running WFO then I'd use their M1 5W-30. If you can't swing the syn bucks and you want to run dino I'd suggest using the Motorcraft 5W-20 or Castrol 5W-20. They are both really good oils and will perform more than adequately if you keep the oil changes at 5K and don't extend them .

 
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I didn't say synthetic oil causes leaks. What I am saying is going back and forth or from the stock Oil (which is not synth) to synthetic and then back to regular oil. It takes time for the seals to cure with the synthetic oil. Once the seals are saturated with the synthetic oil, it is hard on the engine to go back to regular non synth oil immediately, you have to give the seals time to ajust. I run synthetic oil in my car and have been in many previous cars. But I do not reccomend going back to regular oil without a turnover period. That is what I'm saying. "Not" that synth causes leaks but the process of quickly changing from synth to regular causes a high probability of leaks. And these leaks might not persist once the seals / gaskets are resaturated with regular oil.

 
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ok

 
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I've heard and read every myth about syn oil that anyone could possibly think up. I use it in my Honda and switched my old datsuns to it as well, didn't notice any difference or have any leaks. I dunno, I would just keep running it if I were you.

 
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no no...there is a leak situation if your engine is old and not maintain properly....high milelage motor tend to leak oil, disregard using syn. oil or not. but syn. oil is easier to leak out of seals due to the nature of syn. oil being ultra smooth comparing to conventional oil.

 
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Old engines don't leak, old gaskets leak. Old rings burn oil and old valve seals leak oil. Syn oil is supposed to have equal sized molecules which makes it have more of a slippery quality. The result is usually less heat and less wear, which isn't usually ideal for breaking in an engine, but good afterwards. Like I said, my old datsuns didn't leak before I switched and still don't leak 1 year later, and those gaskets are old.

 
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Ummm ok, how did we go from talking about changeing from synth oil - reuglar oil to the mthy about synth? Iv'e talked to some people who know and they said it should be fine and also mobil dosn't make a synth blend

 
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you can change back. It won't cause any problems. It isn't suggested that you switch them too often, but it can be done. I don't know why you would want to head back from synthetic anyway.

 
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My car isn't making that much power and synth coats too much so I want to change

 
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No dont do it

 
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The oil is not going to give you power, it just gives your engine a longer life, which is what everyone needs to think about. I guarantee you nobody these days thinks about there engine, everyone thinks about there brakes, tires, and everything else. One day when you have over 150,000 miles on your car and it still runs good, think that you used synthetic oil.

 
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Mobil does make and has made semi syns for a good long while. just recently they revamped their lineups with the "mileage" formulas. reg oil (5k), semi-syn(7.5k) and Extended Performance (EP) synthetic (15k)

 
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I dont ever recommend running the same oil for 15K miles. I dont care how good the oil is.

 
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oh man here we go again.

 
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I don't care about the oils I'm just listing cuz I thought the guy asked about mobil making semi-syn oils...just providing some info is all

 
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