is it bad to go from dino to synthetic

no its not bad to. just drain old dino and fill with ne synthetic. replace oil filter and fill with new synthetic aswell.

Synthetics are compatable with conventional. They are in every way better than conventional. Some will say it will cause leaks, and that is and is not true. It will not cause a leak, but if you have a leak, it may leak worse because the actual molocules of the synthetic are smaller, which helps it lubercative abilities, but also allows it to get to and through tight places, weather it's the berrings or the gaskets, it does not discriminate. Synthetics tend to have better cleaning capabilities. This myth of synthetics causing leaks is kind of like the transmission flush causing the tranny to go out. I really doubt a bone dry gasket just started leaking because of the oil brand/type. Maby a slight one because a noticable one, but otherwise, no.

Another dont sweat it vote. Like said, synthetic's superior detergents and add pack can clean the crap off of seals, and show you the leaks they already had (its like fiber for your motor. ).

Jason, more about the trans myth stuff please. I always thought there was some truth to that (that a neglected trans can be better off not having a flush - the fresh detergents can clean varnish and crap out and cause failure).

Or are you saying that if a trans is in that bad a shape anyhow, you might as well flush it and if it craps out, you needed a rebuild anyhow?

HISSIN50 said:

Or are you saying that if a trans is in that bad a shape anyhow, you might as well flush it and if it craps out, you needed a rebuild anyhow?

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Exactly. It won't cause a problem, but it can make the problem worse. Flushing an auto tranny is a prevenative maintence item only. Some people neglect to take care of thier tranny, then it starts to act up, so they then choose that time to get it flushed. Too little, too late. The new fluid lubercates better, causing the bands that were slipping to slipp even more. If they had kept the fluid clean then the varnishes and detergents would have kept the surfaces clean and properly working in the first place. In my experience in a shop, as well as many other veteran techs experience, this is the reality.

A customer once confronted me on this, beliving the rumor. I just said "well, I'd rather do the $3000 tranny over a $100 flush, so sure, don't flush it" and that is my stand on it. If we did a flush, and it caused the tranny to go bad, we would be liable.

Switch to synthetic, it bestter in every way shape and form. I run Mobil 1 in my ranger and 20w-50 in the mustang with K&N filters in everything.

Thanks Jason. So if a trans has some nasty fluid in it, (if I read ya right), the trans might actually last longer if that old fluid is left alone (a flush could allow that old trans to crap-out real fast).

HISSIN50 said:

Thanks Jason. So if a trans has some nasty fluid in it, (if I read ya right), the trans might actually last longer if that old fluid is left alone (a flush could allow that old trans to crap-out real fast).

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excactly

There is a TON of documentation out there on people WITHOUT leaks switching a high mileage/older vehicle to synthetic and then having leaks occur. I have had it happen to no less than 4 of my vehicles that I switched -- all with over 80k on the odometer. And all were maintained at a very high (my friends say anal) level of care/feeding.

I've also read post after post on multiple forums where others have had similar experiences. It's well documented that many people who accumulated high miles on dino oil without leaks suffer leaks after switching to synthetic.

The problem seems to be this -- over time, very small openings in various gaskets/seals actually don't leak because those small 'pores' become sealed with the additional sludge/gunk that can accumulate during lots of years/high miles with dino oil. Synthetic oil is known for it's better detergent properties and for being a bit more slippery than dino oil. After switching to synth, the detergents actually clean up some of that sludge which is serving to keep the engine from leaking oil past old seals/gaskets. With the tiny pores in old gaskets/seals 'unblocked' the new, slippery synth finds it's way out -- and voila -- you have a leak which wasn't leaking before the change. Some will say it's not really a new leak -- that the opening was there already. I'd tell you they've confused a 'leak' with a 'blocked opening'. If it wasn't leaking oil on the ground before, and there are drops after the switch -- well, it's hard not to blame that new 'leak' on the switch. The lawyers refer to that scenario as a distinction without a difference. As a practical matter - to the poor guy who now has oil drips on the ground under the car, the switch to synth caused the leak. I'd have to agree with him.

Now -- this won't happen to everyone. And it's COMPLETELY unpredictable - no way to tell if it's gonna happen to you. But -- the facts are very clear -- if the car's older, and has lots of miles accumulated with dino oil, there's a reasonable chance it's either gonna develop a leak where it had none, or existing leaks will be exacerbated. The only way to find out what's gonna happen with yours is to try it. No way around that little fact. What's happened on others is simply not predictive of what's going to occur on the next one. So, to paraphrase my buddy Clint -- "do you feel lucky"?

Having said all that -- if the car has been working well on dino oil for a good long time, why switch? While synthetic is good stuff with some properties that are superior to regular oil, the fact is that there are LOTS of cars that run up many hundreds of thousands of miles on regular old dino oil. In fact, most high mileage cars do it on dino oil. It's only us enthusiasts (for the most part) that are enamored with synth. The highest documented mileage car on the planet put all 2.3 million miles on with regular old dino oil.

...and by the way 90MustangGT....the molecules of synthetic oil are actually bigger, MUCH bigger than the molecules of dino oil. Long-chain polymers they're called - and they're big. And, it's their complex structure and extra size that provide many of the benefits that synth has over dino oil.

That's not the issue however - openings in gaskets and seals are SO MUCH bigger than the individual oil molecules that molecular size is a non-factor in the leak equation. I'd guess hundreds of thousands of 'molecules' escape the engine each time it runs just in vapor form -- all without any leaks showing up on the engine, and without the dipstick showing any loss over a 3-6k mile change interval. Molecules are SMALL. But the synth molecules are MUCH bigger than dino. If you want an idea of just how small molecules are relative to the world humans deal in -- google Avogadro's Number for us, and come back and tell us what you find out. 6.02 X 10 to the 23rd power is a BIG number of molecules....it has to do with gases, not liquids, but it gives you an idea of just how small molecules are.

actually avagadro's number is refered to as the number of molecules of carbon-12 in exactly 12 grams of carbon-12 which is just the reference element because its particularly easy to accurately measure. But you are exactly correct that the hydrocarbon structure of synthetic is considerable larger and more consistant in size. The biggest problem with dino oil is that there are many different molecule sizes from very small to very large in the same oil....this in combination with the large amount of wax found in Dino oil is what ultimately makes it a much lesser quality oil. really good info though....if u are running dino oil right now...dont switch its not worth it. Build a new motor and break it in with dino but switch over to a full syn after a couple thousand miles....thats what i have done and it seems to be working very well....especially in all temperature conditions.

Ref. to Avagadro's number was only to show how HUGE the number of molecules is in even a small amount of any substance. Molecules are so small that we have absolutely no frame of reference. As a practical matter to humans molecules are infinitely small.

Roland - no one can tell you the right thing to do. Try it if you like. If it leaks, switch back and hope the leak goes away. If it doesn't, enjoy the benefits of synth including better high temp/lo temp protection and longer change intervals.

Wow, I thought it was the oppisite, but yes I know how small a molocule is, even the largest one's are pretty small, and the atom itself.... anyways I though that might be a factor. Working in a shop, we haven't had an issue swapping cars to synthetic in higher milege.

If your getting oil leaks, check the PCV system. A clogged PCV system will cause excess crankcase pressure and will surley cause leaks. The most common place for oil leaks is the valve covers, oil sending units, then oil pans. If it starts to leak, then it needs to be resealed anyways.

....GREAT counsel on the PCV system -- malfunctions there cause increases in crankcase pressure which will force oil (synth or dino without discrimination) out of brand new gaskets and seals...

I'd add - the average citizen doesn't really even notice if their car is leaking oil or not unless it's a significant leak. We all tend to baby ours and watch them like a hawk. But Joe and Jane Average are lucky to even check the dipstick between changes, let alone look under the car, or notice if small leaks are occurring. So it's entirely possible that it's an issue on cars that come in -- but people simply don't notice it.

I'm curious -- since the price is so much higher, how do y'all sell them on the swap-over? Extended change intervals? The protection benefits? What's the pitch? Just curious how they typically respond...

I ran synthetic exclusively in my racer -- tranny, wheel bearings, engine, rear end. And we run it in my wife's car as it was in the crankcase when new. My car is just being switched over so I can just buy one type of oil. I usually only put 5-8K on it a year, so I can change the filter every 3k, and change the oil once a year.