Maybe M1 isn't so detergent after all

[pitzel]

GM 3.1L V6, 8500 miles on a fill of M1 5W30 with one quart of M1 10W30 used as top-up oil due to leaks. Car was down another half a quart, so I decided to add a quart of Esso XD-3 0W30 oil.

After I added the oil and drove for 400 miles, the colour underwent an immense change. To me, this is indicating that the addition of a single quart of XD-3 has a very powerful cleaning effect compared to the Mobil-1 that has been sitting in the engine.

Anyone else have any similar experiences, of adding another brand of motor oil and suddenly experiencing significant darkening of the entire fill of oil? I am assuming that the XD-3 0W30 wouldn't be oxidizing or breaking down, so it must be increased detergency of the XD-3 that is causing the colour shift.

Any other ideas? The original fill of Mobil-1 had barely changed colour after 8.5k, so either M1 doesn't have much detergency, or very weak detergency compared to that of XD-3.

 

[Idrinkmotoroil]

Castrol 5w-40 BC did that in my car, it turned very black very fast when I used it, whereas Mobil1 was always cleaner looking when used previously. Dunno what caused the Castrol to be so dark so fast. But I doubt the Mobil1 is a problem, I've torn down engines that used Mobil1 and I was always amazed at how clean they were internally, pretty spotless. Most guys on here will tell you the colour of the oil is not indicative of anything and not to worry about it.

 

[JHZR2]

additive packages are often heat-activated, thus some color change.

WHy do oils with low oxidation, nitration, insolubles, and low wear look dark brown/black?

JMH

 

[Triple_Se7en]

Maybe what happened was an additive clash mixing the two. Sounds serious thou & needs to be investigated... lol This could be the end for Auto-RX... lol

Thanks for the heads-up post! You are the first poster whom I read that two synthetics of different makes may possibly clash.

I am a backyard oil mixologist. I will store this information for future reference. Now back to Oil Chemistry class at Binky's Garage for me.