Dodge Challenger Forum banner

21 - 27 of 27 Posts

·
Registered
2016 Challenger SRT
Joined
·
3,670 Posts
I hate the feeling MDS gives when enabled. My engine tends to noticeably vibrate, which disappears the second it’s disabled. I immediately disable it by pressing my SRT button twice which puts it into ‘custom’ mode. My wife, on the other hand, can’t tell the difference, so when she drives (which is NEVER while I’m in the car) the MDS is enabled.
Since I’m the primary driver, I don’t expect long term engine issues from it.
 

·
Registered
2015 RT 5.7 M6
Joined
·
5,562 Posts
I doubt police cars are running full synthetic engine oil, most likely conventional, it's entire service life. I bet those motors are all gunked up with sludge.
 

·
Registered
Joined
·
9,097 Posts
Some years ago I was involved in a vehicle trip recorder/data logger product and one targeted specifically for fleet operators. Tech support got more than a few calls regarding "idle time" which the device recorded. The operators were quite surprised by the big idle time numbers believing the numbers to be wrong. They weren't. Fleet vehicles spend an inordinate amount of time idling. Even privately owned passenger cars idle more than one might think.

Years ago when Porsche moved from mechanical lash hardware to hydraulic lash hardware (aka hydraulic lifters) it was concerned about particulate matter small enough to pass through the regular oil filter but large enough to cause problems with the hydraulic zero lash hardware. This mechanism relied up extremely tight sliding fits to work. Among other things the tight fit to help act as a "seal" to keep the oil under pressure from bleeding out of the adjuster as the cam lobe pressed down on the lifter as it opened the valve.

Porsche fitted a bypass filter with a much finer filtering medium. As a bypass filter it didn't get all oil routed to it -- unlike the regular filter -- but just some. The idea was this bypass filter would remove the finer particles and prevent any issues with the new hydraulic lifters. But over not much time Porsche found the bypass filter unnecessary and eliminated it.

But I wonder if perhaps a bypass filter might be called for with engines with roller lifters with the very small and heavily loaded needle bearings?
I would think that the SRT filter would be a benefit to the MDS system on the Hemi.

It does have finer filter media. No proof of this helping, but it sure can't hurt.
 

·
Registered
Joined
·
1,568 Posts
I doubt police cars are running full synthetic engine oil, most likely conventional, it's entire service life. I bet those motors are all gunked up with sludge.
Conventional motor oil is not necessarily a sludger. (I ran conventional oil (Ford brand) in my Mustang GT for 150K miles with no signs of any oil/engine issues. The oil got changed on schedule which I think was something less than 5K miles.)

Modern engines benefit greatly from the much improved crankcase ventilation system that removes among other things water vapor from the crankcase (oil). Police car engines spend a lot of time driving on surface streets. I note in my Hellcat this can have the oil temperature quite high (way above 212F) and in the case of police cars the oil gets hot but so to does the entire engine which helps the water vapor remain water vapor all the way out the engine crankcase.

Thus I would expect police engines to be if not in perfect shape from their years/miles of service to at least be free of sludge even if running with conventional oil.
 

·
Registered
2015 RT 5.7 M6
Joined
·
5,562 Posts
Conventional motor oil is not necessarily a sludger. (I ran conventional oil (Ford brand) in my Mustang GT for 150K miles with no signs of any oil/engine issues. The oil got changed on schedule which I think was something less than 5K miles.)

Modern engines benefit greatly from the much improved crankcase ventilation system that removes among other things water vapor from the crankcase (oil). Police car engines spend a lot of time driving on surface streets. I note in my Hellcat this can have the oil temperature quite high (way above 212F) and in the case of police cars the oil gets hot but so to does the entire engine which helps the water vapor remain water vapor all the way out the engine crankcase.

Thus I would expect police engines to be if not in perfect shape from their years/miles of service to at least be free of sludge even if running with conventional oil.
Ok maybe not sludge but more oil staining/vanish. Have a 2002 jeep liberty that ran conventional for 120 kmiles, it's been running synthetic for +15 kmiles. Compared to my JGC which ran conventional up to 40 kmiles then synthetic for +50 kmiles there was way more oil stain/varnish on the liberty than the JGC when I pulled their covers. Also when I switched the liberty to synthetic (although I did run 2 treatments of MMO just prior)...the first oil change after the switch to synthetic was pitch black. Never seen oil that dark in all my oil changes I have done.
 

·
Registered
Joined
·
1,568 Posts
Ok maybe not sludge but more oil staining/vanish. Have a 2002 jeep liberty that ran conventional for 120 kmiles, it's been running synthetic for +15 kmiles. Compared to my JGC which ran conventional up to 40 kmiles then synthetic for +50 kmiles there was way more oil stain/varnish on the liberty than the JGC when I pulled their covers. Also when I switched the liberty to synthetic (although I did run 2 treatments of MMO just prior)...the first oil change after the switch to synthetic was pitch black. Never seen oil that dark in all my oil changes I have done.
More staining/varnish is I suspect due more to the type of engine. OHV engines do not get a lot of oil up top and even at high RPMS there is just isn't that much oil under the valve covers. There is a lot oil vapor that rises from the heat down below. This is going to I think result in more staining/varnish under the valve covers and even on the head surfaces.

However, even with OHV engines which I have seen with the block torn down and the inner crankcase walls visible the cast iron is very clean. The oil being slung off crank and rods blasts or washes any varnish away before it develops.

OTOH, I've seen one of my Boxster camshaft covers off the engine and the underside has very little staining/varnish mainly at a few out of the way areas. The difference is the camshaft cover covers 2 cams working 24 valves and there is a lot oil being slung about under the camshaft cover this works to eliminate any varnish/staining before it develops.

Added: Here's a pic of the underside of a camshaft cover. The camshaft came off with around 250K+ miles on the engine.

Camshaft Cover 2.jpg
 

·
Registered
Joined
·
4,594 Posts
I hate the feeling MDS gives when enabled. My engine tends to noticeably vibrate, which disappears the second it’s disabled. I immediately disable it by pressing my SRT button twice which puts it into ‘custom’ mode. My wife, on the other hand, can’t tell the difference, so when she drives (which is NEVER while I’m in the car) the MDS is enabled.
Since I’m the primary driver, I don’t expect long term engine issues from it.
Although I have the 5.7l, I use a Tazer and the car turns on "Sport" mode every time it is started. I want to get my car tuned, hopefully in the spring to turn off MDS. When more funds come available I want to d a cam swap as well to a non MDS performance cam, and replace all the lifters after seeing YouTube videos of lifter failures in 5.7L
 
21 - 27 of 27 Posts
Top