Blade7

Is it true that once you go synthetic you can't go back to using regular oil? or vise versa?


I'am getting ready to change my oil with red line and was wondering if , I happen to use regular petrolum on an incident, if that will kill my apex seals?

JONSKI

No.

peejay

The only problem with synthetic is if you start using it in a high miles engine. It cleans the insides of the engine so well that the varnish that USED to keep seals from leaking vanishes, and the engine leaks like a sieve. (Similar to the "never change the fluid in an old automatic trans" thing).

I foolishly did this. 160k mile car, figured "Hey, this car doesn't leak oil, I'll switch to synthetic and be okay". It was winter, and cold startability improved greatly and oil pressure stayed more stable with respect to engine temps.

For 2000 miles.

The engine that used to stay full of oil for 3000 miles, leaked all four quarts of oil out in 2000. Switching back to regular oil did not fix it, because the "damage" was already done. At least the regular oil cost a lot less, so I was pouring less money on the ground.

We recently switched a 40k engine (also a boinger) to synthetic, no leakage problems. The general rule of thumb I hear is around 75k-80k is too late.

Synthetic oil still comes out of the ground - sometimes it's synthesized from natural gas, but normally it's merely "hand picked" molecules in the base stock.
Either way, it comes from the same place as regular oil.

Blitz0309

Yeah, what peejay said. I personally don't like synthetic, it dosen't provide much of a benefit, and costs more.

Import Convert

GO GORDON!!!!!! YEAH!!! I would also like to add that synthetic oil is FAR better for the turbos than dino. It is much more resistant to "coking."

PVerdieck

Well I heard that if you were using synthetic and wanted to go back, you first had to fill up with 50% dino, 30% kerosene and 20% Tide to properly get all the synthetic out first. This was from a friend who knows everything about motor oil. More than you guys for sure...

duboisr

I would need a lot of imformation before I put kerosene and tide in my motor. not saying any one is incorrect but I know you can switch back and forth with no problems.

maxcooper

Not all synthetic comes from the same place as dino oil, but it is true that most does. And it really doesn't matter anyway if the oil performs. I agree it is an interesting factoid, though.

There are synthetic blends, so I don't think there is any need to flush all the synthetic oil out of the engine before switching back. I would be pretty leery of putting Tide in my engine.

The late-switch-to-synthetic-and-you-get-leaks thing seems to be true from anecdotal evidence, and is a widely held belief.

-Max

rotorbrain

how about this. change your oil with dyno.. . change it again after 3k. fill it with synthetic. change again after 1500 (cause its gonna clean the hell out of your engine). then refill with synthetic. now after 3k miles change it again and really look at it. it is noticeably cleaner even after only being in there for 2 changes. i would have to say that if you have an engine with so many miles on it then there is really no point in messing with it. youre gonna need a rebuild soon anyways. just keep using dyno if youre so afraid of it. now, when you rebuild it or get a reman then you should go ahead and try it. . . after you break it in of course.

to answer the question that the thread started. . . yes, you can go back, but why would you want to. treat your fd with respect and itll love you for it. it isnt that much more expensive really. just put it into your budget. . . if you cant afford synthetic oils then you surely cant afford to maintain an fd properly.

paul

peejay

Didn't say that.

The varnish in question is hanging out on and around the external seals, ie the seals that are holding the oil in the engine, instead of letting it ooze (pour) out and commence lubricating the underside of your floorpan and your garage floor.

The superiority of synthetic as a lubricant is not in question. As noted, I've had nothing but good experience with synthetic in that regard. However, on switching a "well seasoned" engine to synthetic, expect to do a complete engine re-seal as a consequence.

peejay

I wouldn't trust the ol' eyeball microscope in this regard.

firstly, oil gets darker not because it "gets dirty" per se, but the additives in most oils change color as they absorb chemical contaminants (water, combustion byproducts). coincidentally, this is normally "darker".

oils that don't change color mean one or more of three things: the engine is not producing any contaminants, the additive package does not change color, or the additive package is not doing its job and absorbing contaminants.

the color of the oil means nothing. many oils will turn dark within hours of a complete, thorough oil change, yet will still be "clean".

airborne

i'm currently using castrol GTX 20w50 and draggin today. dave@kdr says mobil 1 (synthetic) is good stuff and thats good enough for me. so i'll be switching maybe this weekend and will be happy to report back on what I see. i have the power fc and am pretty paranoid so i monitor the temps perty close.

rotorbrain

if you look at the synthetic oil after ther first change youll see how dirty it gets. synthetic oil allows your engine to run cleaner as it cleans more and its lubrication qualities keep it from rubbing metal to metal. rubbing metal to metal causes contaminants to enter the oil also. synthetic keeps it from doing that.

of course the oil changes color, but it is noticeably cleaner. you can feel it. im sorry i should have entered that into the first thread. rub it in between your fingers. . . you will notice the difference. . . at least i did.

paul

forcefed1

One thing I can say for synthetic having rebuilt many piston engines.
engines running synthetic look brand new. It's amazing how clean the internals are no varninsh. and the wear on bearings is far less. A very noticeable amount.

One time I rebuilt an engine and poured synthetic in it right away..... NOT GOOD after 10K i did a compression test. 145 across the board when I was hoping for 195.
the rings never seated. the synthetic was so good it kept the rings from seating. After doing some research I learned many others had the same problem. Now when I rebuild an engine I run regular oil for teh first 10K or so to let it break in well adn then switch to synthetic. Of course if I have good compression after 5K ill switch then.

You can't beat how clean the internals are and the protection is bar none.

peejay

Metal to metal contact and the resulting metallic content is an EXTREMELY small amount of the oil contamination. It's all combustion by-products and condensation.

If you're finding enough metal contamination in your oil to notice, then your bearings are probably gone already, and your oil filter is doing a **** poor job, unless it's so clogged that it bypasses, in which case your bearings are probably gone already.

I *have* poured metal contaminated oil out before... 30k without an oil change, the oil came out flowing like water and it was gray and sparkly. the filter was full of gunk, and the engine was pretty much junk.

Tom93R1

iTrader: (2)

If I ever put laundry detergent in my engine I will allow everybody on the forum to kick my ***.

Any way, the reason I finally switched to synthetic was an attempt to help extend the life of my high milage turbos. Synthetic is much more able to handle the extreme temps created by the turbos and as was stated earlier more resistant to coking.

Import Convert

I'm pretty sure this was actually a sarcastic comment..........

rynberg

I'm not sure what your definition of "well seasoned" is, but I just changed to synthetic about 1100 miles ago on my 60k engine. I have detected absolutely zero leaks. Perhaps if I had much higher mileage, there would be a problem.

PVerdieck

I was being sarcastic. Maybe it would have been more detectable if I'd included sand or styrene has one of the ingredients