differences in preferred oil weights.

[dave1251]

Originally Posted By: Giorgiz
I'm raising the question if I can put in my Mercedes Kompressor an oil thinner than 3.5 HTHS recommended by the specific mb.


You can but I would not blindly recommend you try it. If you follow the OEM this is the safest bet.

 

[TFB1]

Originally Posted By: Clevy
Originally Posted By: CATERHAM
Originally Posted By: Swissdieselfan

The thick vs thin dispute is an American auto industry civil war only, the Japanese have always commited suicide with their cars and the folks in the rest of the world just use the best oil for the job AND get the best long engine life advice from their car stealers.

There is no thick vs thin dispute within the American auto industy just with some old school advocates.

How have the Japanese commited suicide?

And "folks in the rest of the world", presumably Europe, use heavier oil grades because they always have and no one likes change (even for the better) unless it's forced upon them.


That sounds like the closest to truth to me.


I see it as more of a case that the Euro mfgr's spec looog OCI so need a oil that if it suffers fuel dilution or shearing, still has the viscosity to protect the engine...

I seriously doubt European engineers are just conducting business as usual...

 

[CATERHAM]

Originally Posted By: RobertISaar
it's a tradeoff between pressure when hot and flow at all times. if your pump runs up to the bypass pressure, you're losing flow. this will generally only happen when the oil is cold or at high RPMs. a thinner oil will create less pressure(since pressure is simply a measurement of resistance), meaning more can flow before it starts getting bypassed.

at least, those are my observations. unless i have issues that are directly caused by low pressure when hot, i tend not to move towards a thicker oil.

You're absolutely right.

Originally Posted By: Shannow
Originally Posted By: tig1
I guess the question has to be ask. Are there any cases of engines failing or wearing out before their time in the last 12 years, since Ford and some of the Asian engine builders have gone to 20Wt oils? None that I have heard of.


Show me a single case of an engine failing or wearing out before it's time with 30s, 40s, 50s ?

While doing so, please refute that thicker oils increase the margin of asperite contact...


And how much excess viscosity margin do you want?
If you can't use maximum rev's with the oil up to temperature without the oil pump going into by-pass mode, then you're running an oil that's too heavy to the point of being clearly counter-productive.
And since most (if not all) late model vehicles now have electronic safety systems in place that reduce power preventing the oil from getting too hot and therefore too thin, it makes zero sense to run an oil heavier the lightest oil specified by the manufacturer.

 

[Shannow]

see, that's the car manufacturers telling you that they've overstepped the mark in the quest for economy, in that the oil starts off too thin to protect the engine at it's rated output for extended periods.

 

[CATERHAM]

Originally Posted By: Shannow
see, that's the car manufacturers telling you that they've overstepped the mark in the quest for economy, in that the oil starts off too thin to protect the engine at it's rated output for extended periods.

Do you have any evidence that the car manufacturer's are "over stepping the mark"?
Because there is no shortage of evidence that they are not.

 

[demarpaint]

Originally Posted By: Shannow
see, that's the car manufacturers telling you that they've overstepped the mark in the quest for economy, in that the oil starts off too thin to protect the engine at it's rated output for extended periods.


Are you referring to electronic castration?

 

[CATERHAM]

Originally Posted By: demarpaint
Originally Posted By: Shannow
see, that's the car manufacturers telling you that they've overstepped the mark in the quest for economy, in that the oil starts off too thin to protect the engine at it's rated output for extended periods.


Are you referring to electronic castration?

Assuming that he is, how many members have had their car go into limp mode when driven hard under extreme conditions? Not many.
I do know a few occasions when it has happened and it's all at the track.
Of course if your ride is prone to the problem running a heavier oil tends to exacerbate the issue.

 

[demarpaint]

Originally Posted By: CATERHAM
Originally Posted By: demarpaint
Originally Posted By: Shannow
see, that's the car manufacturers telling you that they've overstepped the mark in the quest for economy, in that the oil starts off too thin to protect the engine at it's rated output for extended periods.


Are you referring to electronic castration?

Assuming that he is, how many members have had their car go into limp mode when driven hard under extreme conditions? Not many.
I do know a few occasions when it has happened and it's all at the track.
Of course if your ride is prone to the problem running a heavier oil tends to exacerbate the issue.


So for the sake of this discussion, if a high performance Ford engine specing a 50 grade oil goes into limp mode at the track running a 20 grade oil in it will improve the situation, or destroy the bearings? Or is it a moot point since the engine would be electronically castrated in both examples?

 

[Clevy]

Originally Posted By: CATERHAM
Originally Posted By: demarpaint
Originally Posted By: Shannow
see, that's the car manufacturers telling you that they've overstepped the mark in the quest for economy, in that the oil starts off too thin to protect the engine at it's rated output for extended periods.


Are you referring to electronic castration?

Assuming that he is, how many members have had their car go into limp mode when driven hard under extreme conditions? Not many.
I do know a few occasions when it has happened and it's all at the track.
Of course if your ride is prone to the problem running a heavier oil tends to exacerbate the issue.


My buddy has a new 5.0. We beat the ever loving heck out of that car and couldn't get it into limp mode,and if it was gonna happen it would have.
We went from hot lapping to wot on the highway and everything in better. We burned off the rear tires over a weekend,he was putting dot legal slicks on,so we were trying to shred them.
Anyways just thought I'd add that it takes quite alot to force limp mode.

 

[CATERHAM]

That would not be a smart thing to do. You could do it but basically you're taking control over the electronic nannies that are in place that are based on the spec' Motorcraft 5W-50.
You would have to determine what maximum oil temp's you could still run on a 20wt oil; obviously considerably lower than the spec' oil.

One could look at the Mustang GT which still has over 400 hp and is spec'd for 5W-20. We do know that oil temp's something north of 230F must be generated before the nannies kick-in in that application.
Installing an OP gauge to get a handle on actual operational viscosity would be a smart move as well.

 

[EType]

Reading through Mercedes forums, owners report their AMGs going into limp mode on the track when oil temps run at the 275f region.

Other owners report very high temps on the street, up to 230f.

Mercedes and other German cars run hot. Many US cars run cooler. It seems that the different weights are appropriate for the expected street temperatures for both American and German cars.

 

[EType]

Apart from there being thermal castration for Mercedes and not just vehicles running 20 weight oil, I was also surprised to find that Mercedes considers consumption up to a quart per 660 miles not excessive.

Maybe this constant supply of fresh oil helps reach those long oci's!

Having said that, my Mercedes does not consume oil at all, at least not during its latest 8200 mile oci.

 

[CATERHAM]

Originally Posted By: EType

Mercedes and other German cars run hot. Many US cars run cooler. It seems that the different weights are appropriate for the expected street temperatures for both American and German cars.

They can run hot if you can keep them "on the boil" WOT for long enough. That's generally just not possible on the street in NA.
Driven at speeds that will allow you to keep your drivers licence they don't run hot at all, at least the normally aspirated cars don't.
Even the M3 BMW that's spec'd for 10W-60 comes factory filled with a 30wt oil.

 

[CATERHAM]

Originally Posted By: EType
I was also surprised to find that Mercedes considers consumption up to a quart per 660 miles not excessive.

Somewhat off topic, but high oil consumption when driven hard at constant high rev's with high oil temp's is one reason why heavier than strictly necessary oils are specified.

 

[EType]

Caterham

In traffic and slow speeds, my Mercedes runs far hotter than on the freeway. And with a normally aspirated large engine, it runs at its coolest on the freeway at pretty much any max speed I can achieve.

Some AMG owners were reporting oil temp in traffic of 220f. By the standards of a US car that is hot. By their own standard and the spec oil design, it is normal.

 

[CATERHAM]

Yes I've experienced that effect as well in the hot summer months particular when it's sunny at midday.
220F is somewhat above normal but nothing to be concerned about for a 20wt application let alone a 30wt or 40wt.

 

[Giorgiz]

etype can I ask you which model mercedes, oil and insert into the cup?