another oil (synthetic) thread
 

Sorry to revisit this...

Changed the oil in my sons 300e 156k about 4 months ago.... Rotella 5w-40 synthetic.

This car never burned a drop in between dino changes (at 3k). I used 20w-50 dino.

I decided to change over to synthetic for the first time in September.... It has burned a quart and a half in 2700 miles..

What gives? I will go back to dino when it gets warm again.

While I have a couple of theories, there is noooooooooooo way I'm getting into a pissing contest over this. :D

syn oil
 

Yep, me too. Syn oil just makes it past rings, guides, seals much better than dino. It's a superior lubricant though. I mix half dino and half syn; or, do whatever ratio you want to achieve oil useage that you're willing to live with.

I hate to tell you but that Rotella 5w-40 synthetic, isn't a real synthetic.

Its basicaly a dino oil, group 3. True synthetics like Mobil 1 0w-40 and Amsoil are group 4.

So you can't blame the burning on synthetic, I suspect since you went to a much lighter oil you are burning it.

If you want to test this run Mobil 1 15w-50 next change, this is a true synthetic and similer in weight to your old oil. I suspect your oil burning may go away or be greatly reduced by this.

Correct me if I am wrong, but doesn't the new Mobil 1 trisynthetic contain about 30% Group 3 base stock?

Afaik the 5w-40, 15w-50, and 0w-40 are the only group 4's left. The rest are like that Shell just group 3's.

I'd be interested to know if that is true though, maybe they changed more then the bottle?

well, I am just going to go back to dino that is on sale at 1.29 quart.. i was just trying to lengthen the time between changes.

I have always been a 3k change person. I'll keep the fake synthetic in until we warm up in April or may then go back to 20w.40. I'll use some lighter weight dino for the winter.

No big deal.

Do check the Owner's Manual for M-B suggested oil change intervals. You may find them to be longer than 3k, even for dino oil.

Amsoil, and the like I'm sure are pure Synthetics. Also Castrol Syntec 0W-30 and 5w-40 are also true synthetics. You must make sure the 0w-30 says "made in Germany" and the 5W-40 says "Made in Belgium". They are also only available at Autozone. Visit http://www.bobistheoilguy.com/ and you will learn all you ever cared to about oil.

Oh yeah and the GC/BC are also meet the MB Oil Specs !