Synthetic in a high mileage motor?

[spddmn713]

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?

[Blitzkrieg Bob]

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.

[winfred]

some motors like it and do fine and some drink it past the rings at a suprising rate, give it a shot

[Craig]

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.

[zmuff]

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........

[632 Regal]

If it leaks past the gaskets I'd say you need new gaskets.

[GAGE308]

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

[peterllo]

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.

[bahnstormer]

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...?

[Dick Schneiders]

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.




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...?

[Elekta]

I have no oil leaks; I use synthetic. Wife's 535 has a minor leak at the timing chain cover/pulleys, and she gets the Pennzoil. Knowing she has a minor leak is enough for me to not mess with it. At some point she will need a water pump or some reason to tear down the front and when that happens, we'll go after the leak then. I won't use synthetic on her car (yet) because it never has had synthetic and I dont want' to exacerbate a problem that really isn't bugging either of us.

this is a classic YMMV debate.

[JAlfredPrufrock]

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

Jeez talk about EMPHASIS.

BTW I think when I change my oil this weekend I will refill with 0W40 syn, will let you guys know if any leaks develop (engine just turned over 120k).

[632 Regal]

you can go from syn to reg to syn to reg etc...

[GAGE308]

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.
WELL peterllo! that is Why I said "UNDER THE IMPRESSION"..."WAIT A MINUTE" and "does anyone else care to chime in"....because I DID Think about what I was Saying and just wanted some Others to write in and get Info....JUST SO Someone didnt Damage their ****...Thats all...I thought I''d just Slow someone down because Ive heard that from NUMEROUS SOURCES....FORGIVE ME!

[632 Regal]

isitanewthinglikewhenpeoplestartedpostingwithoutsp aces?Eitherwayitskindacooltobedifferent
andbythewayifullyunderstoodyouwerelookingforinputf romothers.

[cadman20]

As far as high mileage engines and synthetic goes, I switched to mobil 1 15w-50 at 200,000 miles in my 1991 535i without any leaks forming. Now at 240,000 miles still no leaks.

[ron kirk]

I have a 91' 535i, my Dad drives a 92' 735iL, both with the m30 engines. Mine has 130,000K, his has 230,000K. While adjusting valves side by side, we were able to compare the state of the inside of the engines and WOW! His looks like it just came off of the assembly line after 100,000K of Mobil1 15W-50. Mine, by comparison which has been religiously BMW-dealer serviced all of its life, looks like somebody dumped carmel topping on it and spray-painted it copper! I am constantly amazed at how poorly taken care of my car actually was, before I purchased it. I took pictures for comparison I'd be glad to email anyone.

[infinity5]

I'd love to see the pictures, Atoolofperil at Intergate dot com

[632 Regal]

host em and post em!

[danzee]

FWIW, I've had synthetic in my 1995 525i since it was "born." No leaks yet at 185K mi. Same experience with previous E30,