Oil instantly turning black?
 

Had my head resurfaced and installed a new head gasket instead recently and added a bottle of oil treatment additives (comp cams break in oil at first, and then stp oil treatment afterward) during break-in. What I noticed was that when using the additives my oil would turn black or very dark gray almost immediately. I verified this on a 3rd oil change about 1,000 miles in by not adding any oil additive at first and my oil stayed nice and clean, then I took a bottle of additive and poured just a cap full of it into the engine and went for a drive to the store and upon returning my oil was already pretty dark again. I thought the additives were supposed to be protecting my engine not burning oil or wearing engine compenents? I haven't necessarily confirmed if the darkness is because of burnt oil and/or metallic from wear but I don't like it either way.. what gives?

Edit: before the head resurface and new head gasket I was using synthetic oil but after researching break-in procedures and such I decided to no longer use synthetics and instead have been using 10w-40 conventional oils ever since the 'rebuild' (but the dark oil doesn't happen unless I put additive in).

Don't add ANY stupid additives. The additives IN the oil are perfect. Adding stuff changes everything to a degree.
It's probably a moly additive? That is why it turns black.

Generally, if oil turns black, it means it is doing it's job holdung the dirt "in suspension", so you can flush it out with an oil change!


Your oil at 40 weight is a bit thick at operating temperatur if your engine is rebuiit "in spec".

I used conventional for the first 200 miles, then again until mile 1000. Then I put Castrol 5w-30 synthetic in it. Oil stays clean for a long ass time. It's like a brand new engine ... wait - it is :)

I am a synthetic oil fanatic, but use some cheap conventional oil and drive it like you stole it, for 500 miles, till your rings are seated... then you can run synthetic...

I use the additive because the main oils no longer contain Zinc AKA ZDDP

So run Diesel oil. :) Or run some of that Joe Gibbons? (SP) break in oil that 22re recommends.

You are over thinking it. Do 3 oil changes until 3K miles and call it a day. Any modern synth oil after that is fine.
But I get it. Here: find this oil, it's what we use for some racing applications: Motul 300V "Power" 5W-30. And it smells good too.

We can talk oil when you have a huge ported race head on there, decked everything and are running high comp pistons @ 11K RPM.

I used Motorcraft Super Duty Diesel 10W-30 for break in oil. Sold in 5 quart jugs at Walmart. Says right on the front of the jug contains more than 1,000 PPM Phosphorous for better wear protection.

http://pqiadata.org/Ford_Motorcraft__SDF_10W30.html

Most of those additives are junk. I wouldn't use STP anything on a chainsaw. There are some good break in additives but most anything on the shelf at Walmart should stay out of your oil. As said before, oil these days have all kinds of additives already in them and are pretty much perfect for regular day to day use. Again, as said before, if you wan't more zinc go with a diesel oil or a specialty oil that has it.