I too love oil threads.

Let's put it this way: My Jeep has 167k miles on it. I always ran a conventional or synthetic blend (usually 4x4 synth blend). This most recent change, I took out conventional Pennzoil 10w30 (the worst oil I've ever used in it) and replaced it with Mobil-1 5w30. So far, it's been the best oil I've ever put in it.

The ticking is almost completely gone from the engine (except when stone cold on sub-25°F days). Also, I was getting 14.5-15MPG with the conventional. Without changing my driving conditions at all (cruise at the same speed) I am now getting 15.5-17MPG. My last tank claims 18.0MPG according to my receipt, but I think I may have missed a possible gallon at fill up. That would still put me at 16.67 though...

I never thought it would make such a difference in such an old engine that doesn't even have overhead cams. I was wrong.

Tomguy,

Go to http://www.whnet.com/4x4/oil.html for a complete list of MB approved oils for your car. (You can't go wrong following the manufacturer's recommendations!)

The findings listed there may surprise you:
"...some oils which are not recommended:
Mobil 1 SuperSyn 0W-30 SL/SJ/CF A1/B1/A5 9.7 doesn't meet 229.1 nor ACEA A2 or A3
Mobil 1 SuperSyn 5W-30 SL/SJ/CF A1/B1/A5 9.8 doesn't meet 229.1 nor ACEA A2 or A3
Mobil 1 SuperSyn 10W-30 SL/SJ/CF A1/B1/A5 10.1 doesn't meet 229.1 nor ACEA A2 or A3
These 3 oils do not meet MB spec of > 3.5 cP for high temperature high shear strength."

You will find very few xxW30 weight oils that are approved.

Personally, I find 3000 mile changes to be a total waste of good oil, as the additives of today can easily go two or three times that and more. If you really want to know, start doing oil sampling and see real facts for yourself rather than taking someone's opinion.

Gerry

The Mobil website suggests either 5w30 or 10w30 for my Jeep, depending on what temperature I put on the chart.
I used 5w30 for the winter - considering the Jeep is never garaged and I usually only drive it to work in the harshest weather (ice cold temps less than 20F, snow etc). I have no leaks, and I am only about 0.5q low after 1200 miles. I'd never put 5w30 in if I didn't have faith in my engine for it to not burn it like gas, or blow it by every seal (since I maintain the vehicle quite well). For my Chrysler, the Mobil 1 site recommends 10w30 - and that's what I used in it. It's also what the manual calls for. If I try a 2007 Chrysler 300 Limited (same engine) it still says 10w30. Now, if you can tell me why 10w40 is better for either one than the oils I put in, I might change viscosities. But I will not put a dino oil in my engines!