Different oil colors in engine

huntingbum

Cadet
Joined
Feb 6, 2011
Messages
8
I have a 2006 4.3GS.
I noticed that the oil on the dipstick looks like brand new, fresh oil. However the oil in the filter is really dark black......

The engine ran great but I noticed that the oil pressure dropped last time out and had oil in the bilge. Not sure where it's coming from but it was definitely dark black.

How can this happen?
 

jimmbo

Supreme Mariner
Joined
May 24, 2004
Messages
13,943
I doubt very much the oil in the dipstick tube has ever been in the oil pan. Unlike an auto/truck engine, the dipstick in a lot of marine engines doesn't extend into the crankcase. The dipstick tube is routed under the block to the bottom of the oil pan. The oil in the tube is at the same level as the level as in the crankcase and varies but never drains completely into the crankcase, thus remains cleaner. Even when running full throttle there is still more than half the oil in the pan. A small block chev takes a little less than a litre to fill the entire oil system. This routing of the dipstick tube allows for easier evacuation of the oil through the tube using a pump( drain/dipstick fitting
I guess you could blow that oil into the crankcase using compressed air, then it would refill with a dirtier mix

A leaking oil hose is the first suspect, then the remote adapter, where the filter normally mounts. Other common areas, valve covers, intake manifold end gasket/ sealer, rear main seals, or leaky fittings on the oil pan
 
Last edited:

huntingbum

Cadet
Joined
Feb 6, 2011
Messages
8
Thank you for the detailed explanation. That makes sense to me. I appreciate helping me out as a newbie here on the boat scene.
 
Top