Why does my oil get dark!

[Black1987Stang]

As you can tell from the title my oil seems to get dark alot quicker then it should be. Since the rebuild the first 2 oil changes did it and i figured it was normal from the assembly lube getting in the oil and just still being broken and stuff. Even right after a fresh oil change i can see the difference in shade after like 2 weeks. The weird thing is if i check it as soon as i turn off the engine its nice and clear but if i check it after the car has sat for a few hours its alot darker?? BTW i had just switched to Mobil1 synthetic after 2,000 miles and still does the same thing. If it matters i took off my upper and the ports look wet, i dont no if its gas or oil? and i also have a see through inline glass gas filter in the pcv line but it doesnt look gunked up. Should i whip out the leakdown tester to check for any blowby.

 

[mustangjoe87]

Just cause your oil is changing color doesnt mean that it is used or overly oxidized. thats normal.

 

[speedytang]

That is Blowby. Smell the oil and it probably smells like gas. I can drive my car 3k miles between oil changes and it is supercharged and it still has a gold tint. My wifes car goes 5k miles between oil changes and looks new. It is not the brand of oil either because I use whatever is on sale since my wife and I drive over 3k miles a month each. I have done leak down test and both cars are perfect even with over 140k miles on each car and my winter car is a 94 Tracker with 120k miles and the oil looks like crap after about 1k miles and yet it burns no oil but doing a leakdown it show one cylinder weaker than the other 3 and my guess is it is a valve seal but no smoke at startup or at wot. How is your exhaust at startup and WOT.

 

[HISSIN50]

I agree that color does not necessarily mean something bad. It means that the oil is doing what it should and suspending matter. But it is disconcerting. Some motors seem to dirty it up and some dont.

 

[Black1987Stang]

Speedystang, theres no smoke at startup nor do i see any at WOT.Also there new positive type valve seals also, The only thing i have is a weird smell on a cold start for a minute but im sure thats from not having cats. I agree with you Hissin on how some motors would like to dirty up some oil and some not, but i had this block completely stripped, i took out all frezze plugs, oil gallery plugs evrything,clean everyhole with a oil gallery cleaning brush, hot tanked it, steam cleaned it, after i bored and honed it, i steam cleaned it and all once again to get all the shavings and honing oil out. Its practically a brand new motor, i just dont want sludge building up from having grimy oil, ya know. Ill do an old school trick by taking a lighter to my dipstick to see if theres any gas in my oil also. Just in case i might do a leakdown test if i can get access to shop air and/or ill also do a compression test, just to check if theres anything fishy going on in there lol