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actually you are wrong! The s-class m157 comes with a oil pressure test port I've used it and so has the shop.
In my opinion, it’s safer to say that they do not have it because they do not all have it and only some models do. This engine was sold mostly in the E class so most of these engines do not have it…. And while this is an oil pressure solenoid thread, this is an E class thread. So while I may not be completely right (which I knew), neither are you….but I provided a solution and you have not. So, what should the majority of the people on this thread with this engine do to pressure test it???? Thanks. As soon as you answer, I will be happy to go out to my engine and do this immediately..
if you’d like to actually help, you could take a picture of this oil test port and make a comment that this test port is available on S class engines.
Last edited by Baltistyle; Jan 13, 2026 at 07:55 AM.
In my opinion, it’s safer to say that they do not have it because they do not all have it and only some models do. This engine was sold mostly in the E class so most of these engines do not have it…. And while this is an oil pressure solenoid thread, this is an E class thread. So while I may not be completely right (which I knew), neither are you….but I provided a solution and you have not. So, what should the majority of the people on this thread with this engine do to pressure test it???? Thanks. As soon as you answer, I will be happy to go out to my engine and do this immediately..
if you’d like to actually help, you could take a picture of this oil test port and make a comment that this test port is available on S class engines.
While I do not have an E class, this oil pressure solenoid applies to every m157. The "dummy" harness (another spare solenoid or a resister) is required and not optional on the s class as it trips a hard code with a CEL same code, but because of the oil pressure switch and the changed oil filter housing (it is the same housing just has the block off bolt removed which is the test port for the sensor) it has issues and yells at you. Removing it should let you test it no matter the chassis.
The part number you sent over was for an m156 oil cap. Mercedes makes them for the m156/m159. I am not 100% sure if it works on the m157. Looking at the documentation on wis it does show you can do the block off bolt removal to mechanical oil pressure gauge no matter the chassis. I've linked it for you.
The 63 motorsports kit I referenced earlier replaces that plug with a banjo bolt and a short section of braided line used to get to a less confined space where a normal pressure sender is connected and then wired to gauge in the cab.
Now that we know that most but not all MB engines have a pressure port, it becomes more interesting to hook an oil gauge or oil sensor.
There are legitimate fears that a failed solenoid can be stuck in low-pressure mode... "1% chance or less" is not likely but not impossible either!
There could be a shortcut to check that dual-rate oil pump is working well in MOD-1 pressure:
Do a comparison of "Before vs. After" at 2k.Rpm.
What are the tell tale signs of stock oiling vs MOD-1?
-1- SOUND... listen to engine HEADS: smooth camshafts, quiet hydraulic lifters, quieter HPFP
-2- LOOKS... open oil filler cap at cold idle wetter/dryer.
-3- FEEL... throttle is providing smooth Rpm control without pressure ridges from solenoid (MOD-1) and squirters (MOD-X).
-!- NUMBERS... you can collect accurate live oil pressures from your engine tap port.
> DEFAULT SETTING...
- A pump defaulted to Normal-pressure mode can not shift to Low output without a solenoid command to work against the heavy return spring.
- Meaning once the pump is resting in normal pressure, it remains in its default mode.
Enjoy better oiling.
Last edited by CaliBenzDriver; Jan 13, 2026 at 03:29 PM.
What 5W-50 oils you M157 & M278 guys have used successfully? Im finally going to move that way from 5w-40. Does it need to be API SP ?
It would be nice to make some list with 5W-50 oils that are good to use with these engines. Years have gone by and many might have good knowledge to share.
I would appreciate it much and maybe many other as well that have thought to go 5W-50 but still not haven't.
Millers EE 5W50 is to MB229.3 spec, this is produced in the UK. Not sure where outside UK it's sold.
Specifications:
Recommended by Millers for applications requiring:
ACEA A3/B4, ACEA A3/B3
API SN, SM, SL
Ford WSS-M2C931-C
Mercedes-Benz MB 229.3, MB 229.1
Porsche A40
AMG, Aston Martin, Caterham, Cosworth, Ferrari, Lotus, Renault, TVR
actually you are wrong! The s-class m157 comes with an oil pressure test port I've used it and so has the shop.
Sorry I definitely was wrong. I dont know how I totally missed this info. I thought it only applied to certain engines ad not the 157. AND I linked for the wrong model which I hate doing...! In a general description they listed the cap on a 157, but now I do see they have a gauge package.
What do you guys think about CASTROL EDGE 5W-50 SP
And here is some info about it:
https://msdspds.castrol.com/bpglis/FusionPDS.nsf/Files/A2190794B97D628580258D0700244A28/$File/wepp-csgw3c.pdf
Go ahead, test drive your selection!
Castrol Edge 5W-50 SP is a Group III oil.
Viscosity will be around for some time.
A Group-IV 5w-50 SP formulation would give you a superior temperature stability:
Motul Power
Amsoil signature
Mob1 Supercar
(Redline)
(Ravenol)
You can use cheaper oils as engine rince off for shorter mileage like 3kMi. It takes time to clean-seal rings so long they quit building additional layers.
-- The difference will be cooler, cleaner sealed pistons rings.
-- Less oil consumption deposits onto valves & chamber surfaces.
-- Effective spray cooling at driving Rpm will get oil hotter than coolant.
-- Engine heat will eventually get under control.
-- Cylinders contributions will eventually balance out for responsive ECU fuel mapping.
-- Engine vibrations will smooth out at all Rpm signaling it is firing on all cylinders instead of laggy lean throttle response.
Enjoy experimenting your upgrade
Last edited by CaliBenzDriver; Jan 22, 2026 at 07:40 PM.
So I picked Up My car today after walnut blasting. Talking with the shop owner and I mentioned I had disabled the oil control solenoid. His reply was " good call, We are seeing other makes have problems with these too"
Go ahead, test drive your selection!
Castrol Edge 5W-50 SP is a Group III oil.
Viscosity will be around for some time.
A Group-IV 5w-50 SP formulation would give you a superior temperature stability:
Motul Power
Amsoil signature
Mob1 Supercar
(Redline)
(Ravenol)
You can use cheaper oils as engine rince off for shorter mileage like 3kMi. It takes time to clean-seal rings so long they quit building additional layers.
-- The difference will be cooler, cleaner sealed pistons rings.
-- Less oil consumption deposits onto valves & chamber surfaces.
-- Effective spray cooling at driving Rpm will get oil hotter than coolant.
-- Engine heat will eventually get under control.
-- Cylinders contributions will eventually balance out for responsive ECU fuel mapping.
-- Engine vibrations will smooth out at all Rpm signaling it is firing on all cylinders instead of laggy lean throttle response.
Enjoy experimenting your upgrade
Ive driven this oil as it was on sale at Napa. Worked fine for me. It was when we were first trying sp 50 weights and Castrol was early to label them that way. I tend to pick what is local vs what others might use. I really like Motul and Penzoil as well but I dont think pennzoil had an sp 5/50 last time I changed my oil..
Ive driven this oil as it was on sale at Napa. Worked fine for me. It was when we were first trying sp 50 weights and Castrol was early to label them that way. I tend to pick what is local vs what others might use. I really like Motul and Penzoil as well but I dont think pennzoil had an sp 5/50 last time I changed my oil..
I noticed all W50 oils run well while new. There's no bad 5W-50 SP.
STABILITY:
How oils run with heat and how quickly they age set them apart.
Written specs only relate to fresh oil in lab environment.
Last edited by CaliBenzDriver; Jan 22, 2026 at 11:20 PM.
I will go either this Castrol 5W-50 Edge S API SP or Motul 5W-50 8100 Power API SP.
No problem, Throughout this thread there probably a half dozen good options. A bit hard to find, but they are here, and as Cali stated, now, with testing, we can see their longevity. I change oil at 3k miles so while longevity is important to me, the convenience of local oil often wins because Ill randomly decide to change oil vs have a real plan. Id also argue that most high end oils are built for a short life when driven hard, so its about using the right oil for you.
Pulled the harnesses off my camshaft magnets (C43 M276) and theres a small amount of oil on the magnet side but not yet on the harness.
Presume best course of action is just to replace the sensors, solenoids, magnets and add the sacrificial harnesses?
Is there anything that can be done at the ecu harness side to help delay it?
56k miles…
cheers
you’ve got the right idea. You might wanna proactively spray the engine side connectors on the harness with an electronics cleaner. And for the ECU connection, just disconnected and spray it out with some cleaner.. follow the directions on letting it dry.
Pulled the harnesses off my camshaft magnets (C43 M276) and theres a small amount of oil on the magnet side but not yet on the harness.
Presume best course of action is just to replace the sensors, solenoids, magnets and add the sacrificial harnesses?
Is there anything that can be done at the ecu harness side to help delay it?
56k miles…
cheers
Sacrificial harness extensions are the last layer of defense to stop oil already leaking out.
Thing is oil should not leak out of premium low mileage engines, right?
Can owners do better ??
There is an experimental solution that can help remove stored heat to prevents heat soaks at engine stop... just that.
Marginally cooled pistons at "normal driving Rpm" accumulate extreme heat that is then released to the block after engine stop.
The uncontrolled pistons heat causes too many issues to be ignored.
> IGNORED PISTONS HEAT...
Nothing directly measures pistons heat. Lambdas measure the high combustion temperatures, pistons are much lower than combustion gases.
The evidence of heat is simply that the more pistons are sprayed, the hotter the oil becomes and the less burnt oil residues accumulate into rings grooves.
The single spray nozzles in use are particularly ineffective at cooling our GDI application.
Friction lube is fine yet there are evidence that scoring is done by oil hard residues. Either stored on the intake valves or on top of combustion chambers.
The key to avoid scoring is better oil control.
Less oil traveling up around jammed pistons rings and less heat to vaporize oil through PCV onto intake valves. Stock hot pistons are setup to accumulate burn oil residues...
Collateral signs of extreme stored pistons heat...:
Big fan always running!
Fuel rail/HPFP hissing!
LED headlights fans after stop
Darker LED Headlights output: heat!
Oily ECU + Lambda... $10k+
CPS leaking "oil-in-harness!"
VVT Solenoids leaking oil
Pmp Solenoid leaking oil
Oil level sensor leaking oil
Turbo coolant lines cracked
Ignition coils insulation failure
PCV discharge conduit clogged
Coolant system issues (Exchanger seal /pump walk /radiator crimps /Mayo mix! /tank discharge... headgaskets ok!)
....
> Few Options:
Owners can not replace stock parts for a more effective setup:
pistons single squirters
oil pump limited volume
water pump tiny impeller
pumps under rev'ed pulleys
We are stuck with very few options:
Do Nothing or
Experiment Out
The key is to control heat that can't be measured.
Stock gas saving setup removes limited heat.
We can experiment greater.
A more effective oil pump gear ratio would be very useful.
Last edited by CaliBenzDriver; Jan 24, 2026 at 04:37 PM.
Enough of your post nonsense please Cali. The cam and magnet sensors on MBs are a wear item and no amount of your oil solenoid and thick syrup oil fantasies are going to change that.
Enough of your post nonsense please Cali. The cam and magnet sensors on MBs are a wear item and no amount of your oil solenoid and thick syrup oil fantasies are going to change that.
TripleD... my fantasies don't involve your magnet sensor in syrup.
My days of SCUBA limit my taste. I am stuck with a dislike for drama.
You can really enjoy factory setup, now without surprise.
Experimental is unchartered with surprises.
Here is my oil upgrade after 2,200.Mi @79kMi: Mobil1 "Supercar" 5W-50 API-SP
Possibly my favorite oil so far
Let's see how viscosity holds towards 5kMi ??
2,199 Mi oil service + Purflux filter (+ Neo magnets)
Still honey colored PAO holding up heat great
Filled to the halfway mark.
Vaporization losses minimal, not wholesale.
standard oil aging coloration (misc fwd ref)
Oil gets burnt when it can't cool sizzling pistons... then it is time to service near 3, 5 or 6k Mi.
Fresh stock oil burns just as soon as previous one unless something's changed to improve the setup.
Less heat, less vaporization shown to keep my valves abnormally cleaner.
Last edited by CaliBenzDriver; Jan 24, 2026 at 10:35 PM.
TripleD... my fantasies don't involve your magnet sensor in syrup.
My days of SCUBA limit my taste. I am stuck with a dislike for drama.
You can really enjoy factory setup, now without surprise.
Experimental is unchartered with surprises.
Here is my oil upgrade after 2,200.Mi @79kMi: Mobil1 "Supercar" 5W-50 API-SP
Possibly my favorite oil so far
Let's see how viscosity holds towards 5kMi ??
2,199 Mi oil service + Purflux filter (+ Neo magnets)
Still honey colored PAO holding up heat great
Filled to the halfway mark.
Vaporization losses minimal, not wholesale.
standard oil aging coloration (misc fwd ref)
Oil gets burnt when it can't cool sizzling pistons... then it is time to service near 3, 5 or 6k Mi.
Fresh stock oil burns just as soon as previous one unless something's changed to improve the setup.
Less heat, less vaporization shown to keep my valves abnormally cleaner.
with respect it’s not uncharted . I mention this back in 2023 to save you guys the trouble. It was already tested and confirmed. Any good brand 5w50 is better then 0-40. I tried saving you guys time you could have been using 5w50 for the passed few years already lol. Real world results goes a long way fellas . Not knocking you brotha just stating that sometimes listening to people like Tasos , and other people with years experience on this motor could save you guys a lot of time and trouble . Hope this doesn’t come off offensive it’s not my intention. I think it’s now safe to say Mobil 0w40 has caused its fair share of scoring because of it failing to do its job and protect cylinder walls appropriately
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