Is "clean" oil an indication of anything?

Joined
Mar 5, 2007
Messages
640
Location
Western Washington
I've asked this question before, but never got a solid answer. I know that just because an oil turns dark doesn't mean that isn't not performing properly. The flip side is if I'm running known quality oils (i.e. Pennzoil Platinum or Valvoline Maxlife) and the oil stays "clean," is that an indication that the engine is deposit free or that the oil is still performing? To simplify, has anyone documented a bad UOA on oil that still appeared essentially new? Note: I'd post a picture for fun, but have not figured out the trick on this forum yet.
 
Joined
Jan 29, 2009
Messages
2,804
Location
NJ
The oil is always at work, whether it turns dark sooner or later is really dependent on your engine. It may mean that as you keep running the same oil in the engine its getting cleaner and cleaner, but don't base it on color alone.
 

blackdiamond

Thread starter
Joined
Mar 5, 2007
Messages
640
Location
Western Washington
 Originally Posted By: Anies
The oil is always at work, whether it turns dark sooner or later is really dependent on your engine. It may mean that as you keep running the same oil in the engine its getting cleaner and cleaner, but don't base it on color alone.
Why, is there any UOA evidence for an oil sample that appeared new but was no longer performing at the level that it should? Many people get concerned about dark/black oil and thus can only feel comfortable with a UOA, but it would be nice to know what the various samples looked like.
 
Joined
Jan 29, 2009
Messages
2,804
Location
NJ
I'm sure there are UOA's but you would need to perform a search on them or google search the exact behavior your questioning. For me buying my Xterra used, my initial fill of Synpower was black after 2k miles and was dumped at 3.5k. PP was run for 3.5k and was just as dark. Now I have an MMO PP/Syn blend in the engine and after 3k miles its still clear/turning amber. Trying to clean it up as best as I can so as to put the truck on a steady diet of a good oil thats easily accessible. My tC's oil with about 5k on it was black with Synpower, and it was black at 3k with synpower. I trust a UOA, other peoples results and information on engines than basing it on a color.
 
Joined
Oct 9, 2004
Messages
6,497
Location
New Braunfels
In reality there are to many variables that can affect colour. Many times before a change I would consider what is on the dipstick as amber, but the drain oil then looks black or close to black. WHat I put in Sample bottles is dark, it is not translucent like new oil. I can also see a difference on the dipstick colour between Hot oil and cold oil. (Hot oil always being lighter) . These are just observations and mean nothing to the performance of the oil.
 
Joined
Mar 14, 2008
Messages
166
Location
Way down South
I see many people brag on their choice of motor oils , and comment that it was still clean when they changed it . So what ? I would rather see evidence that it is cleaning my engine and suspending the crud for the filter to pick up .
 
Joined
Apr 18, 2008
Messages
1,093
Location
Kentucky
I have a daily use 1986 Toyota pickup with over 300,000 miles. I have a daily use 1999 Chevrolet Cavalier with 213,000 miles. I changed the oil and filter in both, yesterday. The oil was still clear enough to make it difficult to see on the dipstick. In the drain pan, it was a darker, amber color. By the time I got around to dumping the drain pan(about 3 hours) into the 5 gal container to take to the recycle place, it was dark molasses color. With 514,000 combined miles, still running great, I don't think clear oil in an engine is an indication of any kind of problem or failure to clean engine. More like it is keeping engine clean. The Toyota never goes more than 4.5 miles at one time. The great majority is less than 2 miles with 2 to 6 hours between start-ups. It has been on this schedule since June of 2007, 7 days a week.
 
Joined
Oct 18, 2007
Messages
3,756
Location
CA
FWIW, using the same oil as I have for years in the GN, going to Total Seal gapless rings, the oil stays new looking for the entire short OCI. Blowby seems to have a huge effect on how quickly the oil changes color.
 
Joined
Jan 3, 2009
Messages
14,882
Location
Illinois
Since my engines never see anything but M1 they stay very clean. With the 10,000 mile OCI my oil very slowly turns to a dark amber colar thru the OC. If your engine is already gunked the oil will get black quickly.
 
Joined
Aug 5, 2008
Messages
691
Location
Aridzona
As Buick suggests, I think clean oil strongly implies that the compression rings are doing a good job of minimizing blow-by. If the rings are coked up or worn out the oil will get dark in a hurry. I think it also suggests that your engine is clean on the inside, with light or non-existent deposits. Unless you're running something stupidly cheap, any new oil should be able to solve at least some of the junk that may have built up when the last oil was getting tired. Thirdly, and somewhat less certainly, clean oil is probably not being thermally stressed inside the engine, and is unlikely to precipitate sludge. I remember once riding my old air cooled Kawasaki across the Mojave desert in the middle of summer. Temps were in the 120 range. (Not the brightest time to go for a spin!) I started out in central Ca. with a fresh change of Castrol GTX. The poor oil was completely destroyed by the time I reached St. George, pouring out soot black with a gell-like texture. Next time I set the valves I noticed, for the first time, a light layer of sludge-like goo in the head area.
 
Joined
May 28, 2009
Messages
52
Location
Kalifornia
 Originally Posted By: blackdiamond
I've asked this question before, but never got a solid answer. I know that just because an oil turns dark doesn't mean that isn't not performing properly. The flip side is if I'm running known quality oils (i.e. Pennzoil Platinum or Valvoline Maxlife) and the oil stays "clean," is that an indication that the engine is deposit free or that the oil is still performing? To simplify, has anyone documented a bad UOA on oil that still appeared essentially new? Note: I'd post a picture for fun, but have not figured out the trick on this forum yet.
If the oil runs longer without browning, it means the engine is clean and you are not blowing by the rings (which puts carbon into the oil and turns it black).
 
Joined
Aug 5, 2008
Messages
691
Location
Aridzona
Blow-by also adds acids to the oil, reducing TBN and shortening it's lifespan. Clean oil is happy oil!
 
Joined
Oct 28, 2002
Messages
48,021
Location
Everson WA - Pacific NW USA
 Originally Posted By: blackdiamond
I know that just because an oil turns dark doesn't mean that isn't not performing properly.
I've been stuck on this sentence for a couple days. Clean appearing oil could actually have relatively high dissolved metals. Dirty appearing oil could have been in use 12K miles and have almost no wear metals, low solids, low metal particulate....but also dirty appearing oil could mean the oil is actually cleaning up scunge left behind by lack of maintenance. Appearance of the oil basically tells you the oil has been in use if it's dark. Not much beyond that if it appears light. Some oils have additive packages that change color with use. If the oil remains light colored in use, then mostly the guess would be the car has low blowby and there isn't much clean-up going on (not much to be cleaned), or the oil has add packs and base oils that don't change color.
 
Joined
Feb 21, 2004
Messages
2,149
Location
USA
The combustion engine is not clean. Different engines efficiency may differ. Fuel, moisture, heat and dusty conditions plays a part.
 
Joined
Jul 20, 2007
Messages
1,408
Location
NH
i know oil companies heavily promote keeping the engine clean...i have never had black oil in my car, even after 8k on Mobil one...usual oci is 6k dino, 7k synthetic...i think if oil is real black it has been in too long IMO
 
Joined
Feb 21, 2004
Messages
2,149
Location
USA
Neglected engines with irresponsible oil changes of course. And when new oil is replaced it's dirty itself. A self defeating objective. And after 100,000 miles the engine does build up. You're not going to have the same cleanliness of an engine when new at 3,000 miles versus at 100.000 miles. "The combustion engine is not clean. Different engines efficiency may differ. Fuel, moisture, heat and dusty conditions plays a part."
 
Top