what kind of oil should i put in my car?
MBWorld Fanatic!
Joined: Mar 2006
Posts: 4,278
Likes: 377
From: San Jose area
'19 E63S sedan
You should use any oil you're happy with, but a couple of things you say are a bit confused.
For one, viscosity at operating temperature is an important specification and can't be ignored in the name of another specification, whether it's VI or some scar measure under some set of conditions that may or may not be relevant for the engine you care about. I assume you wouldn't put Amsoil motor oil in a differential that calls for SAE 90 hypoid gear oil because it had the lowest wear scar, would you? Why not? Because you realize that a wear test on 30weight oil has nothing to do with gears that require 90 weight lubrication.
It's the same thing with engine oil viscosity. VI should be high, yes, but not at the expense of the right viscosity. 30 weight oil will result in low oil pressure in galleys that were engineered for 40 weight lubrication. VI has nothing to do with that. Wear scar tests have nothing to do with that. Lower viscosity oil will shear (lose film strength) at a lower temperature than higher viscosity oil. VI and wear scars have nothing to do with this. A high VI says that the oil will maintain it's viscosity at a high temperature, but if it's the wrong viscosity for the oil galley diameters and other engine design specs, that doesn't help much. In other words, you want the highest Viscosity Index for the specified viscosity rating. Chosing a higher VI and a lower-weight oil makes little engineering sense; you're chosing to run your engine at reduced oil pressure because it's a superior oil for an engine designed to use it.
Thanks for passing along the Amsoil information. I hope it continues to perform well for you.
For one, viscosity at operating temperature is an important specification and can't be ignored in the name of another specification, whether it's VI or some scar measure under some set of conditions that may or may not be relevant for the engine you care about. I assume you wouldn't put Amsoil motor oil in a differential that calls for SAE 90 hypoid gear oil because it had the lowest wear scar, would you? Why not? Because you realize that a wear test on 30weight oil has nothing to do with gears that require 90 weight lubrication.
It's the same thing with engine oil viscosity. VI should be high, yes, but not at the expense of the right viscosity. 30 weight oil will result in low oil pressure in galleys that were engineered for 40 weight lubrication. VI has nothing to do with that. Wear scar tests have nothing to do with that. Lower viscosity oil will shear (lose film strength) at a lower temperature than higher viscosity oil. VI and wear scars have nothing to do with this. A high VI says that the oil will maintain it's viscosity at a high temperature, but if it's the wrong viscosity for the oil galley diameters and other engine design specs, that doesn't help much. In other words, you want the highest Viscosity Index for the specified viscosity rating. Chosing a higher VI and a lower-weight oil makes little engineering sense; you're chosing to run your engine at reduced oil pressure because it's a superior oil for an engine designed to use it.
Thanks for passing along the Amsoil information. I hope it continues to perform well for you.
MBWorld Fanatic!
Joined: Jul 2005
Posts: 2,319
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From: OC
AMG E55, Stage 1, Strait Pipe from Primary Cats
Last time I changed my oil, my tech(indy) put 5W30 synthetic in my 2000 S500, I think he said 5W40 is what they are starting use too...I am in socal.
MBWorld Fanatic!
Joined: Mar 2006
Posts: 3,254
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From: Louisiana
03 E500 and Corvette
Oil is like which beer you want. You really can drink any beer and use any oil you chose. It is really your choice in a free world. If you don't care about warranty and drive a MB then I assume you can buy another MB if you chose. Remember it is all about choice. Data is what people use to help with choice and there is lots of it. The 4 ball test for oil film strenght is a good test and we can quote pour points,, flash points and all the rest of the engineering "stuff". But it still boils down to YOU can run which ever oil you choose and drink what ever beer you like if you want beer. But for me I drink Bud Lt and use Mobile 0w40. Why.? Taste on the first because I can't get dark German beer. 
. But the oil,, Because it meets Mercedes spec 229.5 and Mercedes requires this oil to get the best life out of the engine. If I chose to use $1.00 oil from the quicky 
it is my choice. But of course it is not recommended.
I have the same V8 that is in the S420 in my E500 and when it wears out I will buy another MB and probably an S500 and Still use the recommend oil.
So Ya'll have a great time and remember you really don't have to follow MB recommendations, but they did BUILD the car and THE ENGINE.
. But the oil,, Because it meets Mercedes spec 229.5 and Mercedes requires this oil to get the best life out of the engine. If I chose to use $1.00 oil from the quicky it is my choice. But of course it is not recommended. I have the same V8 that is in the S420 in my E500 and when it wears out I will buy another MB and probably an S500 and Still use the recommend oil.
So Ya'll have a great time and remember you really don't have to follow MB recommendations, but they did BUILD the car and THE ENGINE.
