Just pour it in and run it.

If the engine is full of crap you will need to do a few short changes.

It is good to know that switching to synthetic doesn't cause leaks to develop or worsen with the Benzs. It sure does with some vehicles. I've tried it with Mobil1 in two vehicles that did so far. A 92 Mitsubishi Expo AWD 4-cylinder with 184k on it and a 92 Jeep Cherokee inline 6 with 180k on the clock.

In both cases the vehicles already had minor leaks (one or two drops overnight) that became MUCH worse immediately. They both began to leak about enough to leave a 2"-3" oil spot overnight. I switched them both back to dino at their next oil change and both they went right back to dripping just a drop or two overnight.

I swore then that I'd never convert another high-mileage engine to synthetic, but if it won't cause the same kind of issues, maybe I'll try it with the Benz next oil change...

I sure like the longer service interval though. I started using Mobil1 in my wife's 2001 Grand Cherokee inline 6 when we bought it at 65K (its basically same engine as the what's in the 92) and it has never leaked a drop.

I do a full oil & filter change, she runs it 3500 miles, then change just the filter and top up the oil to replace what was lost removing the old filter (about a quart). Then let her run it another 3500 miles before doing another full oil & filter change. Even with 7000 miles on most of the oil that I drain out of it, the oil still looks clearer and cleaner than the dino I drain out of my other gassers after only 3000 miiles.

That may well happen on the benz too. If the car already leaks, thiner synthetic will probably leak more (simply because it's thinner). The solution is always the same, fix the leaks.

the way I understand it. Synthetic has some additives to sort of rejuvinate the gaskets. synthetic will clean out some of the crap that could be keep the seal/gasket from leaking and start leaking becauseof it. It can swell up the gasket to a point, but if the gaskets are old and cracked nothing is going to help. maybe they should have been replaced anyway.
the benifits of synthetic far exceed dino oil, but that is my opinion, and information I have read else where to come to these conclusions.

It`s always better to have some kind of oil even if it is the wrong oil than to have no oil at all.

Having a leak isn`t the problem. It`s when it stops leaking, is the problem :eek:.

Charlie ☺

Actually my theory is the 116/SD with 260k miles had been poorly maintained, was owned by Vegas stripper before me. And I've got no doubt in the world bearings were thin from lack of oil changes. Am certain it had been overheated coupla times too, based on coolant level mysteriously dropping that suggested weak headgasket. Nevertheless strikes me synthetic oil erasing 260k miles of dino oil varnish coulda been contributing factor to rare spun bearing problem. This disaster occurred with me hammering down while entering freeway tryin not to be clobbered by semi-truck. Yer probly right though, it was worn out engine from the git-go.

Would I convert 250k+ high mileage engine with questionable maintenance history to synthetic again? .....probly NOT

OTOH, i started my backup car the rusty/wreck 240D on synthetic at 108k miles 5 yrs ago. Now at 190k with synth oil changes, regular maintenance and never bottoming the gears these past 80k+ miles it's the peppiest and best running 240D I've ever seen. Has zero symptoms of gettin old and slow, this 240 engine has sweet-spot at 75-80mph where it actually runs better than at 60-65.

Mine leaked less.....

Same here, my leaks almost completely went away. With dino I had a few drops on the ground overnight and about 1qt lost between fuel fillups. With syn I just have a seeping front main seal and less than 1/4qt lost between fuel fillups.

I've been using Rotella Synthetic as well and the car seems to be happier about it on cold winter mornings. Unlike changing oil in a gasser, the oil seems to go blackish almost immediately. Normal?

Normal. It's the soot byproduct of combustion in a diesel.

In my experience synthetic oils cause oil leaks in high mileage dino oil gas engines. From what I've seen the synthetics remove varnish that covered the oil seals.
I'm guessing that the high base additives in diesel oil prevents the varnish build up in the first place.

Now you have done it.......
 

[QUOTE=300SDog;1850023

OTOH, i started my backup car the rusty/wreck 240D on synthetic at 108k miles 5 yrs ago. Now at 190k with synth oil changes, regular maintenance and never bottoming the gears these past 80k+ miles it's the peppiest and best running 240D I've ever seen. Has zero symptoms of gettin old and slow, this 240 engine has sweet-spot at 75-80mph where it actually runs better than at 60-65.[/QUOTE]
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Bragged on the car. Be careful. It L get uppity on you.

Regards

Run-Em

Synthetic Mobil 1 15w50
 

I've been running Mobil 1 15w50 in both Eleanor ('87 300TD, ~225k miles) and Gladys ('82 300D, ~340k miles) since I got them. They both seem to leak less with it than they did before the changeover to synthetic.

Good to know that the first batch of oil with synthetic should be 3k miles, then 5k after that. Will follow that regimen in the future... still need to fix Gladys's odometer, though, so I can tell how many miles she actually has!! :eek:

What's this about swapping the filter at 2500k miles, so that it goes through two filters per batch of oil? Definitely recommended? I've got a buttload of filters... just order like a half dozen for some reason... so I'm down for the program if that's what y'all think should happen. :-)

cheers,
~Garlynn

Mobil 1 5w40 is a better application for your cars. An interval of 5K miles is fine for both the oil and filter.

I put Mobil-1 5W-40 synthetic in my '96 E300D at 259,000 miles. It neither leaked nor burned any oil before and still does not now. An oil analysis at 4300 miles on the oil showed that the engine wear was negligible and the oil good for many more miles.

OTOH, I put Mobil-1 synthetic transmission fluid in this same car and the transmission began to leak so badly (and would not stop even after I went back to non-synthetic) that I ended up having the transmission rebuilt. Oops!

I also have Mobil-1 in my 1985 300D-T (239,000 miles). It leaks a bit more than it did before but some of that may be the very aged gaskets and o-rings in the turbo area, which I am currently rebuilding. If so, the leaking will slow or stop. I'll probably go back to dino oil on this vehicle anyway, the synthetic was intended for a winter trip to the snow that did not happen.

The theory told to me is that the oil molecule is a long carbon chain. Synthetic oil has shorter chains = smaller molecules so it will leak through tiny places that the larger non-synthetic oil molecules won't. YMMV.

Jeremy

That makes me feel alot better about my recent oil cooler line incident. Thanks alot.:eek: