Originally Posted by raptor
I've thought 5w40 is thicker than 5w30? Aren't you supposed to use 0w30 ESP. Please it's only question. I have no knowledge of these oil just want to learn.
When the 3.0L MB turbo diesel engine came out a while ago, it was spec'd for 5w40 oil and nothing has really changed except CAFE (corporate average fleet economy) goals imposed by the USA gov't to improve fuel economy. The spec then went down to 5w30 and I guess from what you have said, it is down to a 0w30. A 0w30 oil is a bit thinner than a 5w30 at operating temperature but still within the 30 allowable viscosity range for a 30 weight.
I feel that going to lighter oils in engines that are worked hard, i.e. carrying a heavy load is going to result in increased engine wear. I rather sacrifice the .4 mpg and prolong my engine's lifespan.
Case in point: Ford used to spec 5w30 and 10w30 oil in their V10 and not too long ago that was reduced to 5w20 although the design has remained the same. The only plausible explanation was FUEL ECONOMY standards imposed by the Gov't.
If you look at owners manuals for USA vehicles in foreign countries, you'll be amazed that the same vehicle which specs 5w20 oil in the USA specs 5w40, 10w40, or 15w40 in other parts of the world.
I for one, one drink the EPA Koolaid and use an oil with slightly better viscosity than water.
All of my vehicles at home are running 5w40 weights in the summer and my gas engines are switched to 0w40 in the winter. My diesels all stay with 5w40 year round. I tried 15w40 in the warm months but did not see any benefit with engine wear via oil analysis with this oil for my driving conditions.
You can get an low SAP/low ash 5w40 oil for your 3.0 turbo diesel Mercedes Benz engine from Kendall-Kendall 5w40 specifically. It meets 229.51 MB spec which is an e.s.p (emission system protection) engine oil.
The new spec MB 229.52 actually requires oil manufacturers to show a fuel economy benefit over the 229.51 spec'd oil previously used in the same engine. This is, of course, is met by thinning the oil down.
No thanks, I rather get 500k miles out of my engine. Only 400k more to go.
There is a reason why semi-trucks which carry heavy loads use 15w40 oil. However, there is a push to improve their fuel economy with use of 10w30 oils which show a 1% improvement in fuel economy over 15w40. Truckers aren't confident that the thinner 10w30 will give the same engine longevity as the heavier oils.