The color of oil...

[fortunate1]

I have seen how the petroleum-based motor oils that I've used will turn darker as the miles add up. It didn't matter whether it was a 4, 6, or 8 cyl gasser or diesel; that golden color would turn dark brown or sometimes almost black by change time.



What causes this? Soot, particulates that the filter can't trap, thermal (heat) breakdown? Does it matter? Does the darkening mean that the oil is "working"? Do synthetic oils do this too?



I'd like to hear some input, and I'm sure that others would like to know the answers to these questions too. Just trying to get more credits from U. TDR. The $35 tuition is a bargain.

 

[fishjack1]

I believe the main cause for the dark color of used motor oil is heat. Detergent oil will turn a dark blue-black after it is heated. Non-detergent oil will turn a reddish-brown. "Most" diesel engines will turn oil black in the first few minutes of running time. The only accurate way to determine an oil's lubricating value or contamination level is through oil analysis.

 

[Gary - K7GLD]

ll I can say is, the oil in my truck with the Frantz bypass filter will stay extremely clean for a good 2000 miles, but gradually darkens - I can then replace the TP cartridge, and within several hundred miles, the oil will be clean as new again - whatever darkens the oil WILL obviously filter out...

 

[LV-CTD]

After running my '93 for 6k highway miles with Rotella T synthetic I simply changed the filter, Fleetguard Stratapore, the next day the oil looked like it had been changed too. It's nearly another 6k now so I'm going to change both oil and filter together.



Tom

 

[JHerrlich]

It's the soot that turns diesel oil black. Some of it gets past the rings and makes your oil black is night.

 

[Ncostello]

When I change the Delo400 and the Fleetguard fiter... My oil will stay looking new until I reach about 4000 miles. Then it begins to darken.

 

[WStrmiska]

Would I be right to say that the new 2004. 5 diesels with little miles on the engines would turn more black sooner because of the rings not fulley seated, would that be correct?

 

[RustyJC]

The primary cause of engine (gas or diesel) oil turning darker is the detergent/dispersent additive package doing its job. This additive package is keeping submicron contaminant particles (too small for the regular full flow filter media to take out) in suspension until the oil is drained and the contaminants are flushed out with the oil. If not held in suspension, these particles would settle out in the engine as varnish, sludge, carbon, etc. Back in the "good old days" of non-detergent oil, the oil might come out looking cleaner, but the inside of the engine would eventually turn into a sludgy, filthy mess.



Rusty

 

[Ralph Wood]

Black Doesnt mean dirty oil. It can be very black and be cleaner than the oil in a gasser with golden oil. The oil in my Camry always looks like new because there is no soot and the additives are the type that dont turn dark. A guy came to the house awhile back that was in a big hurry to install a Gulf Coast 0-1 on his 8. 3 Cummins in his Motor Home. It was DL Morrison of DL Morrison Propane in Gainesville, TX. He was headed for Alaska. When he got back he left a sample of oil on my back step to be analyzed. It was about as black as black could be. I have been at it so long that I knew it was in good condition. I stopped at Inland Truck Parts in Denton and picked up a Pennzoil Quaker State sample kit. The soot content was 0. 2% WT. It doesnt take much soot to turn the oil black. If the oil feels like new oil and you can rub some on the palm of your clean hand and it leaves a clean film it is clean. If the soot fills the crevices with soot it is time to change the filter. Normally if your filter is good enough on a gasser the oil will always look like it was just poured out of the bottle. The little filters like Frantz, Gulf Coast and Motor Guard will kick some serious butt when it comes to cleaning oil. When the oil starts looking like dark honey I change the filter. The next day it will look like lite honey. If you want to find out how good your fuel filter is put a Motor Guard down stream of it.

I was looking at a FS 1000 fuel water seperator on a big Cummins over the road Peterbilt at work. I was thinking why not install one of those as a primary filter. Then I could install the Motor Guard M-60 after the pump. The Motor Guard is very effective to 1/10th micron but cant handle over about 6 ozs of water. The FS 1000 can handle the water and protect the fuel pump. It says 10 microns on it which is too good for a primary filter. I have done a bunch of Powerstrokes using the M-60 for a primary filter but the Powerstrokes have a very good pick up pump.

I am doing a new Dodge for a fussy fighter pilot/U2 pilot that wont let me drill any holes in the frame. It is going to be a challenge. I can do it with mounting plates and existing holes. Gulf Coast 0-1 on the lube oil. Motor Guards on the fuel and ATF. I think a combination Perma-Cool ATF filter, Motor Guard dual remote system would do it. I have a little time before it is delivered so any suggestions would be appreciated.



Ralph

 

[fortunate1]

My experience has been more like Ncostello, with the oil (Delo 400) gradually turning darker toward the end of its time in the pan. Do the synthetics darken like this too? Same reasons?

 

[Ralph Wood]

I have Delo 400 15-40 in propane Caterpillar fork lifts that havent had an oil drain in many years. The Motor Guard M-30 filters have always been advertised to filter down to as small as 1/100th micron. The oil looks as good as it does right out of the can. This would tell me that the heat and additives are not much of a factor at turning the oil black. I have Shell Rotella T 5-40 synthetic in my Toyota Camry. When it starts looking like dark honey I change the Motor Guard. The next day the oil looks like lite honey again. It would be nice if the Shell Rotella T 15-40 looked as good in my old 84 Ford 6. 9 Diesel. I know it is clean but it is black with a golden tint around the edges on the dipstick. I sent a sample of oil to Titan labs of Denver. They said the oil looked good keep changing the oil as recommended. Everything is geared to allowing the oil to get dirty then draining it.

I have several heavy duty diesel engines at work, they all are different. I have a 4 cycle Detroit that has oil that looks like a gasser oil. It is Delo 400 15-40, it hasnt had an oil drain in about 10 years. There is a small amount of soot that can get thru even the super filters. The engines just keep dumping it in the oil. I have the heavy duty Gulf Coast filters on the large engines. A large Cummins engine seems to be showing the oil is getting cleaner looking.

I went to a new element. It is too soon to know if the new element is cleaning the oil better or some one sneaked in and drained the oil when I wasnt at work. I installed a big Gulf Coast 0-1 on a local diesel mechanics Powerstroke a few years ago. He now has the contract to repair the trucks so he might be the culprit. We have some GCF filters at Cape Canaveral. The engineer said the oil gets cleaner than new. I thought he was joking. New oil is sometimes too dirty to use They send a sample of oil to their lab to see if it needs to be cleaned before putting it in the big engines.



Ralph

 

[Ajwalls]

Color of oil, can't tell too much from its color, if it is black, brown, or golden it could be doing its job. The key to a longer lasting engine is filter, filter, filter. To make sure the oil is doing its job, send a base sample to a good lab, and test your oil every other or so oil change. Amsoil, Rotella, etc. will last forever, if filtered properly-- ask the over the road truckers, with 300,000 to 500,000 miles with no oil changes.



2001, 2500, Bright Blue, Piller Post 3-guages, Fuel pressure guage on steering column, BD ehaust brake, AFE air filter, Edge Chip,Maghytec Double Deep Trans. pan. -- pulling a 28' Travel Trailer, weighing 9,500 lbs.

 

[Tony T.]

Ralph: Do you prefill the new filters with new oil before reinstalling. I have heard some debate on this subject before. Quote: New oil is sometimes to dirty to use. What is the best measure to use pre-fill or a dry filter.

 

[Ralph Wood]

Tony,



You dont prefill any bypass filter. There is a lot of debate on prefilling the full flow filter. I always check the inlet for loose glue or other foreign objects. I found one that it was obvious that someone had tried to put it on the wrong car and brought it back. I wouldnt prefill the full flow filter unless the engine had been sitting idle for a long time or I had just overhauled it. I wouldnt bang the filter on a dirty chassis part as I was installing it. I always thought of new oil as clean but it is canned by humans and humans sometimes get sloppy. It might be worse where the engine holds 400 gals and the oil is brought in on a transport truck.

I was trained by Standard Oil. They taught me to oil the gasket and screw it on. It is not good to tell a customer to prefull the filter because you dont know what they will pour in it. A neighbor was having trouble with his lawn mower. He kept the gas can under the eaves of the house with the lid off.



Ralph

 

[Tony T.]

Thanks for the reply Ralph. I have always pre-filled the Fleetguard filters on my 03 trying to watch for any foreign matter that might contaminant the filter, but I may change my habits on the next oil change. Never thought about the oil being dirty.