Is there any danger in making the switch to synthetic oil from dino oil with 150k on the motor?

going but personally, I would not do it. I tried it one time on a Mazda MPV at around 90k miles and oil leaks started where, prior to the syn, there were none. Replaced the rear main seal to resolve the leak and went back to the Castrol 20-50w.
Jim
'85 300D
'95 E320
'97 CRV

I had a bad leak start, perhaps coincidentally, when I converted my 300TE at 8 yrs old/68k mi. Rear main had to be replaced, and I've since replaced just about every piece of rubber in the motor. But at 169k, it's running strong-albeit it's had the full top-end treatment. And I only use Mobil 1, becasue even though you may have to replace a few seals, the added protection and ultimate longevity outweighs such minor setbacks.

My 500E was converted at 43k mi/7 yrs old, and no leaks by the way. And the D was just converted to Delvac 1, and no leaks so far.

I say, if you're gonna keep the car, go ahead and switch.

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"If God had meant for us to walk, why did he give us feet that fit car pedals?" Sir Sterling Moss

Michael
2014 E63S Estate
2006 SLK55
1995 E500
1986 Porsche 944 turbo

Hmmm, I was going to change to Mobil 1 synthetic at my next oil change... I have 90k miles on my 1995 C-class... maybe I should think twice? WOuld it hurt to just try it out? I can always switch back, right?

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2006 E350 w/ 155k miles (Daily Driver)

Previous:
1993 300E 3.2L Sedan w/ close to about 300k miles
2003 E500 Brilliant Silver (Had 217k miles when totalled!)
1989 300E with 289,000 miles (had for <1 yr while in HI)
03 CLK 500 cabrio (Mom's)
2006 C230k (Dad's)
1999 S420 (Mom's/Dad's)
2000 C230k Sport sedans
2001 CLK320 Cabrio (Mom's)
1995 C280 My First Mercedes-Benz... (155k miles. EXCEPTIONAL AUTOMOBILE. Was Very hard to let go of!)

Switched my '88 260E over at 154k miles with no problems. Use Mobil 1 15W-50 initially, last change used Valvoline SynPower 5W-40 (used by MBUSA now in all FSS cars to meet ACEA A3/B3 standards). What I REALLY want is Mobil 1 0W-40 (to be a true oil "snob" ), but I haven't been able to get it yet (was told dealers are getting it). May go back to Mobil 1 next time. Not sure yet. Both work fine. Got the Valvoline free, Mobil was $4.29/qt. Made for an easy decision.

STAY WITH STOCK FILTERS!

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1988 Mercedes-Benz 260E

Dsinger:

Where did you buy the Valvoline SynPower 5W-40? I live in Massachusetts. I have tried Pepboy, Autozone, Walmart...and couldn't find it.


Thanks
Car Nut
99 E430 Sport

NAPA is the only place that's got it. May have to order it, but they CAN get it.

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1988 Mercedes-Benz 260E

So let me understand this questions correctly. Using synthetic oil causes leaks? I just purchased a 1993 300E 3.2L and had the head gasket replaced and put synthetic oil in it. Did I make a mistake???

Teddyman,
No, you didn't make a mistake, especially if your head gasket was just replaced!
The theory behind using synthetic oils in higher mileage engines is that it will dislodge some oil 'gunk' that was sealing oil leaks, thus an oil leak with the thinner synthetic oil.
There has been a bit of debate on weather or not it causes oil leaks, I guess it all depends. I am going to try it out at my next oil change.

__________________
2006 E350 w/ 155k miles (Daily Driver)

Previous:
1993 300E 3.2L Sedan w/ close to about 300k miles
2003 E500 Brilliant Silver (Had 217k miles when totalled!)
1989 300E with 289,000 miles (had for <1 yr while in HI)
03 CLK 500 cabrio (Mom's)
2006 C230k (Dad's)
1999 S420 (Mom's/Dad's)
2000 C230k Sport sedans
2001 CLK320 Cabrio (Mom's)
1995 C280 My First Mercedes-Benz... (155k miles. EXCEPTIONAL AUTOMOBILE. Was Very hard to let go of!)

David C Klasse,
Thank you. As you may know the cost of replacing a head gasket is up there, so I'm glad you cleared that up. I'll keep putting in the synthetic...

I realize this is an old post. I've been reviewing discussions posted over the past few years here. And I needed to add some thoughts.
I am running on 235,000 miles here with my '84 SEC. I put Mobil 1 15w 50
in it to quiet down some ticking lifters. After about 7,000 miles I have noticed a leak. Before the steering box repair I had leaks all over. So I did not distinguish the source of the oil leak verses steering fluid leak. It all mixed together. I have discovered Castrol High Mileage 10/40. And so my return to dino oil is complete.

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Selling used Mercedes parts on Ebay...always changing...
cdplayer51 take a look!
____________

I put Mobil 1 in my 560SL at 100K miles. I now have 131K miles, no problem. But I am the type of person who belives that if dirt is the only thing sealing my engine, I would have no problem putting in an oil that would disloge that dirt, casue a leak at which time I would fix the leak. So therefore I would never think twice about putting Mobil 1 in any car as long as it doesnt burn espensive oil.

John Roncallo

If you care anything about your engine, and are looking to keep it for 100,000 plus miles, you will use Mobile 1 or Amsoil, and use their high capacity filter. There have been many stupid things said in this post and many misunderstandings about synthetic oil. I'm not a mercedes expert, and still learning about my car. I do know something about lubricants, and shade tree mechanics can say whatever, but I've seen enough engines in my lifetime, and enough teardowns to know that either of those two brands is what you need to be using. Everything else is just not as good. I can say this as someone who worked at a major powertrain plant and have seen it all after teardowns. If you want to use conventional motor oil, your engine seals will get harder faster! FACT. Hard seals leak oil. Changing over to a synthetic will not cause the problem, the problem was already created by conventional motor oil. Ask yourself this......why do they go longer between oil changes in europe? why are we suckers for the 3000 mile oil change? why are we still wasting time with conventional oil????? The oil companies want to sell oil. simple. Any lubricant expert will tell you, change to mobile 1 or Amsoil, and you can go longer between oil changes, especially with the better oil filters. (the problem with americans are ....that we are too lazy to check oil between changes, so we have to change it every 3000, otherwise can you imagine all the lock-ups from running out of oil!!!!!) And!!!! If you really want to talk oil filters, cut them open guys. You will see what a piece of crap FRAM builds. Quit using all the crap and change over to Mobile 1 or Amsoil.

I've changed about 5 Volvos and my MB 300E to synthetic oil with no leaks appearing. All had at least 100K mil;es and one Volvo had over 200K miles. The 300E had 140K miles. I've used both Amsoil and Mobil 1. Mobil 1 is a bit less expensive.

I change out the synthetic at about 6000 mile intervals. I used to change my regular oil at 3000 mile intervals. There is a web site which has published lab analyses of both Amsoil and M 1 over about a 15000 mile change interval and these test show there is no loss of lubrication in that interval. I don't like to go so long so I use the 6000 mile change.

Results:
1. With regular oil, I usually found that the oil got quite thick by the 300 mile change time, very black. The synthetic oil does not thicken and seems less dark at the 6000 mile change.

2. When using regular oil (usually Havoline) I usually needed a quart of replacement oil sometime in the 3000 miles. I rarely need to add synthetic oil in the 6000 mile interval. My theory is that the regular oil's lighter molcules are burning off or else the oil is breaking down to lighter molecules.

3. I can't really report any improvement in gas mileage with synthetic oil.

I think you can do fine with regular oil using 3000 mile change intervals. However, if you live where the winters are cold, synthetic oil will floww much better and definitely helps the engine. I use synthetic oil partly because I like my cars and want to do the best by them.

Many recommend synthetic oil in the tranny and the diferential.

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1986 300E
1993 Volvo 940 Wagon
1984 Volvo 240 (daughter's)
1976 Dodge 1/2T pickup, gas hog

New headgasket at 80k, because I had a VERY minor leak which Starmark was very generous to repair. So, nothing but M1 every 5k on this headgasket, total of 60k miles. No leaks, mostly 15w50, but I think that is overkill especially with a solid gasket/clean motor. Am running the new 5w40 from MB and probably will unless I start developing any leaks down the road

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former: 83 300D, 97 C230, 93 400E

current: 08 C300 Luxury , 92 500SL