Which Synthetic Oil has The best Chance Of Sealing Leaks? - PeachParts Mercedes-Benz Forum

ezrider · #1 03-09-2004, 04:07 PM

Oh no another oil question!

I did a search and found a few scattered comments on this subject. Maybe it's interesting to some here to review this topic in one thread.

I have a 1991 350SDL, 159K miles, original owner. It has a minor front crankshaft seal leak and significant injector pump motor oil leaking.

I'm probably going to switch to a synthetic. Would anyone here care to comment on which synthetic(s) might have the best chance (if any) of slowing or stopping my leaks?

Thank you.

Rick Miley · #2 03-09-2004, 05:13 PM

Mobil Delvac-1 will have the best chance. But it may take as long as 20,000 miles, and will probably leak worse in the meantime.

ktlimq · #3 03-31-2004, 02:55 PM

Quote:

will probably leak worse in the meantime.

Is it usual with any synthetics, including Amsoil 20W-50 synthetic or Mobil 1 15W-50?

dieseldiehard · #4 03-31-2004, 04:28 PM

Using AMsoil 15W40 it still leaked in my OM603. I bit the bullet and had the seals replaced. I hated wasting good synthetic oil.
DDH

nellotare · #5 03-31-2004, 06:07 PM

I used Mobil 1 Synthetic at 240,00 miles (first time in engine) and leaks stopped IMMEDIATELY! Have done nothing to seals or anything else. So it appears "difrunt strokes for difrunt fokes".

ktlimq · #6 03-31-2004, 07:04 PM

nellotare,

Mobil 1 0W-40, or 15W-50? Or something else?

Where did you have leak?

Usually, synthetic oils leak more than minerals because the flow better.

ezrider · #7 03-31-2004, 07:28 PM

I had apparent leaks in several places under the engine and it was a mess there. I had my injection punp motor oil leaks fixed for $671.00 last week and I haven't had a drop on the garage floor in a week, It's so nice to see it clean now where before it was such a mess.

Now I'm really tempted to make the switch to synthetic although the tech who fixed my leaks, and who I have a huge amount of respect for, said he wouldn't bother to switch.

Based on the research I have done I would change the filter several times the first three thousand miles if I did it.

I REALLY like this car.

nellotare · #8 03-31-2004, 08:23 PM

I had several leaks (circles of oil on pavement) under the engine. All stopped except one.. the one that supposed to be there to "mark his territory"

15w50 is what I use and never changed oil or filter before 5,000 miles passed.. IMHO changing before 5,000 is a waste of time, energy, money (especially the cost of synthetic) and worst of all-- can be harmful to environment depending on where used oil is dumped.

Quote:

Usually, synthetic oils leak more than minerals because the flow better

mine is proof this is not necessarily the case

asi es la vida

ezrider · #9 03-31-2004, 09:57 PM

From what I have read, in a large number of forum posts here and elsewhere on the subject of switching to synthetic, the consensus is for frequent filter changes the first 3000 miles to capture the sludge and debris that the synthetic will dislodge from within the engine if the engine has a lot of miles on it. Some people have dislodged enough sludge to completly stop up their filters.

archibald2 · #10 03-31-2004, 11:31 PM

My experience has been one of satisfaction with synthetic oil, specifically, 5W-40 Delvac 1. I will not go into my personal reasons for using this particular oil as it is not germane to this thread.
However, I would not hold a synthetic oil (or any conventional oil for that matter) up to the task of mitigating leaks that existed prior to a change-over.
A Mobil representative told me, as I was researching a conversion to Delvac 1 on my VW TDI 3+ years ago, "If the engine had a pre-existing leak, this oil is not going to make the situation better or worse". I accepted this explanation and applied it to making the change to synthetic on my two Mercedes. Neither of these cars were leaking at the time of purchase and remain that way to this day.

JHZR2 · #11 04-01-2004, 09:50 AM

Here is a study of oil, with respect to seal swelling, conditioning and cleaning, due to their respective additive packages:
seal swellers

And a thread having to do with it:
thread

#12 04-01-2004, 11:52 AM

I apologize if this sounds sarcastic.

I think it is a very bad plan to depend on oil or any liguid agent to repair leaks. Once in a blue moon, you might swell or soften a seal and effect a temporary fix. This will be a very rare situation.

The job of engine oil is to lubricate and deal with crankcase contaminants.

The best way to fix leaks involves gaskets, sealants and wrenches.

Good luck,

JHZR2 · #13 04-01-2004, 11:55 AM

agreed, I second that one... But sometimes ones ability (Im talking about myself here) is not good enough that they can fix the leak, and its too expensive to get done at the time. Then it is nice to know that something can help out at least a bit.

JMH

ktlimq · #14 04-08-2004, 06:42 AM

ezrider,

Quote:

the consensus is for frequent filter changes the first 3000 miles to capture the sludge and debris that the synthetic will dislodge from within the engine if the engine has a lot of miles on it.

What do you think of doing engine flush instead of early oil change for first synthetic?
Which maker's engine flush is safe for old Mercedes diesel?

JHZR2 · #15 04-08-2004, 07:59 AM

Please do not use engine flush. Most ofthese products are very smiliar to kerosine, and not suitable for lubrication purposes. Sure, they are only supposed to be used at idle for a few minutes on a cold engine, but still, they are not very good to use, at all.

I would suggest Schaeffer's 131, which is an ester based package that can be used in both fuel and oil (esters are also the components in group V oil basestocks; group IV and V asre true synthetics, IV being poly-alpha olefins ad V being esters, esters making up high end (redline) racing oils and jet engine oils), or a product called autoRx, which is another natural ester based product which acts like a solvent and then surfactant, which dissolves nd loosens sludge, then surrounds the sludge as a particle, that then gets caught up in the oil filter.

Both of these products are nly used as a small fraction of your engine oil. Either one I would suggest running with a good, cheap HD diesel 15w-40 dino oil, for about 1000 miles. Than, do a 1000 mile 'rinse' with the same oil, to help get everything out. then you can make changes as you desire, such as to synthetic oil.

Going straight to synth is by no means wrong or bad, I just get the impression youd like to try and get some junk out of your engine. However, quite honestly, if youve been using good HD diesel oils and changing them around the 3000 mile mark, there should be no sludge or junk in your pan, even after 200K miles. I know as I dropeed my pan and was amazed at the cleanliness of it.

A 'poor man's flush' would comprise of getting three gallons of wal-mart HD diesel oil. Do an oil change, replace the filter and plug, then pour in a gallon of oil slowly. Let the engine cool, and crank a few times to get it flowed through the various oil passages, etc. Drain the gallon of oil. Refill with the correct amount, and drive at length until it is up to temperature (oil cooler is hot), Id suggest a good 50-100miles. Drain oil and refill with desired oil. The wal-mart cheapo diesel oil will have enough detergent/dispersant to help clean up stuff, and ten youre draining it after it has gone through the oil cooler, etc. Tehrefore your overall oil remains in the engine are pretty clean and new, and youve drained and replaced a lot of the soot,e tc that was in there.

Hope these ideas help,

JMH