I made a good move last week - PeachParts Mercedes-Benz Forum

junqueyardjim · #1 12-25-2017, 02:23 PM

It was time to change oil on my turbo 617 installed in my 240D. When I had that engine installed a little over two years ago, we put in new oil and filter and I think we installed Shell Rotella Diesel 10-40. Last winter it did crank pretty slow, but I don't use the car much in real cold weather. I sold the engine I installed originally in 2008 from my 85 300D, to a friend in Chicago. Really should not have done that because it was a really nice running engine, no leaks, no smoke and used no oil. But I had this 617 Turbo from an 81 300SD in my garage and it was taking up space and I wanted it out of the garage or at least off the floor. So I sold the 85 and I kept the 81 which I knew nothing about except that when I pulled it at the junkyard on a hot August day I jumped the electrical system with cables to this old car and the engine fired right up and sounded good. And that without glow plugs and sitting in the junkyard for six months. So I made the deal to sell my 85 and gambled that this 81 would be a good engine.

So after two years and not many miles, I doubt that I put on 5000, I felt it time to change oil. The engine ran well, very good power, but it was much rougher on the drive line with the 240D flywheel then my original engine was. This engine made the driveline pretty noisy, especially at speeds of 35 to 55 mph in 4th gear with a light load, you know, flat road, city or suburban speed limits and 45 to 50 is about all you can run, and that drive line would rattle. Matter of fact I had just made up my mind that if another heavy flywheel comes up for sale I am going to get it and install asap!

But now last week I changed the oil to Mobil 1 5w40 light truck diesel and like magic the car is so quiet. I really don't have an answer for the really great change in the amount of noise in both engine and driveline. But it is wonderful and now I have the same quiet running machine that I had with the 85 300D 617D. I was really feeling bad about having made that sale but now I have the answer, a large part of it is in the engine oil. I now will not be actively seeking the 617 Euro heavy weight flywheel, though I do know that it will make it even smoother and I would recommend that to anyone, so long as the price is reasonable. But if you are troubled by the buzz in your driveline, maybe you should try Mobil 1 diesel rated oil. It makes a big difference, really big difference.

CDTurbo001 · #2 12-25-2017, 03:07 PM

My 300CD's PO wasn't much of a car guy - changed the oil real frequent, but I'm sure it was probably conventional 15w40. He may have even told me at some point that's what his shop put in it. I put Schaeffer's full syn 5w40 in it right off the bat (after running it a few minutes, picking it up from him and such) and the difference was apparent.

In other vehicles I've also felt a difference after an oil change when it hadn't been done for a while previous, even without changing oil type/grade. I'm not surprised you can tell a difference. Mobil 1 is good stuff, but any 5w40 (I believe that grade is full synthetic by its nature) would make a difference over a thicker grade with some age on it. 5w40 FTW.

tyl604 · #3 12-25-2017, 08:42 PM

In the older engines doesn't the syn oil have a tendency to cause oil leaks, more so that dino oil?

CDTurbo001 · #4 12-25-2017, 09:33 PM

It can, by its nature of being more slick and dissolving gunk that some times seals holes that will otherwise leak. High mileage oils (I believe Valvoline makes a Maxlife 15w40 but I'm unsure if it's synthetic blend or not - their passenger car oils are syn blend but the diesel may not be) have additives that legitimately help seals - aka, it's not just stop-leak.

I have about 2,500 miles on that 5w40 in my CD and it's not leaking enough to leave any drips, outside of the drain plug that leaves a 1" dot overnight. Even with that leak (which is more time-dependent than mileage) I've only lost about 2 quarts. I believe the engine's only legitimately using a quart every 2,000 mi. or so, even with some slop in the turbo shaft.

Myself, over the long term I put more priority on an oil that flows and protects better than one that leaks less. I'd rather have the motivation to just fix the leaks, anyway.

strelnik · #5 12-26-2017, 09:08 AM

Quote:

Originally Posted by tyl604

In the older engines doesn't the syn oil have a tendency to cause oil leaks, more so that dino oil?

I have been using Mobil1 0W40 for three years in all my 123 cars and have had no leaks.

I have also periodically gone through the engine compartment to check for leaks, especially around valve covers. No problem there either.

Diseasel300 · #6 12-26-2017, 09:20 AM

Quote:

Originally Posted by tyl604

In the older engines doesn't the syn oil have a tendency to cause oil leaks, more so that dino oil?

That's largely an old wive's tale. Synthetic can make an existing leak worse in some cases if the leak is held back by sludge or gunk. Synthetic oils tend to have stronger detergents and can dissolve sludge and varnish that can slow down weeps and leaks. It won't cause new leaks though, at least not modern synthetic oils.

Junkman · #7 12-27-2017, 07:25 AM

I run full synthetic in both of mine. It lets them spin faster and start in TNX cold without plugging in.

I forgot numbers but Blackstone said to increase distance to change on my Cummins. I haven't sent a sample fro a 617 it for testing.

CDTurbo001 · #8 12-27-2017, 09:45 AM

I studied it when I got my car and came to the concensus 5,000 on synthetic is safe in a 617 without used oil analysis. After that it's best to know your specific engine's soot contamination, etc. before extending the interval.

mbolton1990 · #9 12-28-2017, 02:27 PM

I keep reading more and more about how these new diesel oils are largely junk for our older engines. Makes you wonder!

CDTurbo001 · #10 12-28-2017, 10:40 PM

How so?