Red Oil

Joined
May 18, 2009
Messages
2
Location
Eastern IA
Been noticing the last few years the used Castrol GTX 10-30 has a red tint to it at the 3K oil change. It will have a red tint on the dip stick at 1K miles. It comes out of the bottle a light amber, no sign of red. Whats going on here?
 

JAG

Joined
Oct 23, 2005
Messages
5,319
Location
Fredericksburg, VA
Different additives change color to different extents when exposed to heat. Red is a common color that forms but some much more so than others. I think this is the cause of the red oil you are seeing. Base oils can turn brown solely from heat but they are rather well protected from that early in the oil's life by antioxidants, so this is more of a factor in motor oil that has taken a beating. Used motor oils obviously also disperse combustion products which tend to make the oil look black. Then there is water...oil/water emulsions tend to be yellow.
 
Joined
Aug 21, 2008
Messages
25,051
Location
ON, Canada eh?
It's all the blood on the dipstick from that Scottish guy whiping everyone with it. That's where the red is coming from. I hate that guy!
 
Joined
Jun 15, 2003
Messages
36,795
Location
ME
I noticed that color from M1 5w30 back around y2k. Was on a 3k OCI. Could have gone much longer.
 
Joined
Aug 21, 2008
Messages
25,051
Location
ON, Canada eh?
 Originally Posted By: oilyriser
Lots of money will flow to the person who invents an additive that reliably turns colour exactly when the oil is depleted.
Most people think when it's black it's done!
 
Joined
May 28, 2007
Messages
5,579
Location
earth
such an indicator would likely be pH related when the TBN and TAN numbers converge to the "used-up" state fo the oil
 
Joined
May 25, 2005
Messages
4,009
Location
Calgary Canada
If you are driving a BMW with an inline 6, they are known for giving oil a red/brown tint. Not sure why though. My 330ci does this to oil and it shows great UOA's.
 
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