Synthetic in a high mileage motor?
I have heard a lot that you should not run full synthetic oil in a motor with high mileage (above 75-100k) because it will leak around/through the seals. Is this true?
3 Grand Master
It's kind of true & false.
True the synthetic oils will find a leak and flow better due to their nature and detergents cleaning the sludge and gum away from leaky seals and gaskets.
False that they are bad for the motors, seals or gaskets, and cause leaks.
Basically, if it leaks you had problems developing anyway and the synthetic oil just does a better job of getting through the holes.
Vee ave vays of dealing vid your kind...........
5-10 Grand Master
some motors like it and do fine and some drink it past the rings at a suprising rate, give it a shot
all america wants is cold beer warm cat and a place to take a poop with a door on it
Big, Big Time Poster
Yeah, you can always go back if your car starts eating oil. I put it in mine and it seems to leak a tad more now, but the benefits far outweigh having to add a half quart every couple months.
1992 535i TCD-s2
Big, Big Time Poster
I agree with these guys. I started running Mobil1 0W40 at about 155,000 miles with no problems at all. The motor had no leaks to begin with and I still don't have any now at 165,000. I never had to add any oil between changes, so I feel pretty lucky. Of course my radiator started leaking a week ago........
zmuff--1989 535i 5-speed--17" E39 Style 32's--JC chip--UUC Short Shift--
--Racing Dynamics Springs & Sways--Bilsteins--Yorktown, VA
Green Beret Special Ops
If it leaks past the gaskets I'd say you need new gaskets.
95 E34 530I V2.37
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Those who make peaceful revolution impossible will make violent revolution inevitable.
John F. Kennedy
wow...hold on...WAIT A minute here....cool infor guys....but can you really JUST GO BACK????,..,..I was under the impression that ONCE YOU GO to SYNTHETIC....YOU ARE THERE....NO GOING BACK....Unless you get a FULL engine flush...even then Im not sure....But GREAT damage can be done with going BACK to Conventional OIl from SYNthetic....I hope I put this IN before anyone Hurt anything....ANYONE else care to CHIME in on this?
Don
Yeah consider that you can get synthetic blends, i.e. conventional oil mixed with synthetic. I have gone back and forth in four cars, no problems.
Think about what you are saying, great damage can be done, how? Oil is oil, how it is refined and what additives are put in it make the difference. There are several websites on oils, check out this one, www.bobistheoilguy.com.
Grand Master
what i have heard is in agreement with the first poster...
once a motor has been running on regular the gaps and
tolerances are used to it. now when u run much less
thick? what was that word viscous? synthetic oil, u will
develop leaks and stuff that wasn't there before? also it
won't seal as well...?
Big, Big Time Poster
That "might" have been true when the synthetics first
were developed, but they have been much better for a long time and it isn't an issue. It certainly was a "wives tale" back then, anyway, and probably promulgated by those who didn't want to spend in the teens of dollars per quart. I have been using Mobil One in my cars just about from the instant it was developed and never had any leaks that I even suspected was a result of the synthetic oil. I didn't alway use it, especially on my clunkers, when it was so expensive, but probably more than 75% of the time.
Originally Posted by bahnstormer
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