What makes oil turn black? I noticed that my oil was getting pretty dark and it's only been 3000 miles. I use Redline which shouldn't have to be changed for 5000 to 7000 miles.

 

carbon deposits and you should change it every 3000 no matter what it says

 

jeez dude you should do it every 2-3K. don't listen to that bs

 

That's not true of Redline oil or other synthetic oils such as Mobile 1. They're supposed to be designed with a higher tolerance and actually protect better after 3000 miles. That's why I use Redline. That 3000 mile limit is generally BS. Even a regular dyno oil is supposed to last longer than 3000 miles.

Someone made an indepedent test of oil and oil filters a while back which showed this as well.

 

Nope your wrong on this buddy. The sythetics in the oil wear out after. And even the mobile one which the sythetics in (that are supposed to last past 3000) build carbon deposits (stuff that makes your oil black) It is best to change it every 3000. ANd i have never ever ever heard it works better past 3000 i dont get how it could can you explain? I mean how can it like clean itself? Does it clean the engine? Im Sorry im just baffled

 

I run Mobil 1 and I try to change it every 3000 miles for peace of mind, but if I go over I dont worry about it. I went 5000 miles once (2500 mile round-trip road trip, didnt have time before, or for a couple weeks after)with no problems at all. But I still try and change it around 3000 miles if I can.. But I dont sweat going over it. Ive also heard of people going up to and over 7000 miles on synthetic oil.. The molecules that make it up dont break down as fast as conventional oil is the reasoning behind it I think, but like I said, I try to stick to 3000 miles for peace of mind.

 

This is all the stuff I have heard from here and there on engine oil:

Black is from it getting too hot and burning.

Blow-by of spent mixture (exhaust gas) or a leak of some kind getting through the rings or valve seal makes it smell like gas and also reduces its friction reduction quality.

Synthetics last longer because the molecule chain is longer and takes more time to get cut up by the gears and lose its friction reduction quality. Maybe some like Redline actually make an extremely long chain that at first has less friction reduction and works better after being cut up more?



Hal

 

Does dirty oil= high NOx readings during a smog check?

-B

 

I'm a firm believer in synthetics, but I know of engines that lived way longer than is normal on dino oils with lots of abuse (i.e. way longer oil change intervals than recommended). The longest living IC engine that I know of personally is a 351 in a 3/4 ton truck that my cousin purchased brand new in 1986 and sold in 1994 with 550K miles on it. The guy who purchased it is presently still driving the truck with the original engine that has never been pulled down, same rotating ***'y, same heads, tranny and rear end with over 850K on it! It only saw dino oil and regular recommended oil change intervals were performed on it....every 4k to 5k mile oil/filter changes. The truck still runs strong and every indication points to it hitting the million mile mark...all on dino oils..........

 

Well, how about the 1998+ Mercedes that go about 10-12.000 miles before and oil change is needed? Doesn't this mean that synthetic is able to go longer then 3000 miles? Mobil 1 is used in all vehicles and service intervals are set by the oil quality sensor.

 

Changing oil every 3-4k miles is waste of time. 5-7k miles is about right. I know LT1's run so clean there is no need. Why would a company that distrbutes oil tell you it would last over 3k if they can double there money. 3k miles is a myth and anyone who has alot of experience with motors and know how they work and what makes them wear knows this. It is all in the oil and filter. Why do you think you only change your filter with amzoil every 6 months?

 

Mobil 1 used to have "extended oil changes to 25,000 miles" printed right on the back of their bottles until someone without common sense did the 25k interval without changing the filter durning the same interval and (supposedly) damaged their engine and sucessfully sued Mobil Oils...
I personally know of someone who never changed the Mobil 1 oil in a plumbing truck for the life of the engine...he just changed the filters at recommended manufacturer's intervals and normally sold the trucks with about 200k miles on them running perfectly with great (normal) oil pressure...