Will a CK-4 oil clean a sludged gas engine better than PCMO?
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I had a beater/commuter back about 15 years ago that was really sludged up, 88 Pontiac Bonneville 3800. I'm talking just paths in the carbon for the rocker arms to move. It basically looked like it was full of charcoal and took a while for the oil to go down when filling. I drove it daily and used Rotella T6 5w40 since BITOG was talking up that oil at the time. I didn't really pay much attention to changes since the goal was for it to keep running reliably, but did oil changes every 5k which was often.
Well, after about 55k miles I had to do valve cover gaskets. I was very impressed with what I saw when I took the valve covers off.I wouldn't say it was Mobil 1 clean where they look like new, but was impressed that it was only down to varnish. I realize formulas have changed since then but I think the same still applies. Diesel oils have more additives in them and will probably still do a better job cleaning than any off the shelf cheap conventional oil. Higher dollar synthetics probably do a good job though such as any of the LL01 oils. Standards have really gone up these days on gas oils. As long as you aren't burning a ton of oil, there is no harm in giving it a shot to see how it does. Many thinner diesel oils now too.
Well, after about 55k miles I had to do valve cover gaskets. I was very impressed with what I saw when I took the valve covers off.I wouldn't say it was Mobil 1 clean where they look like new, but was impressed that it was only down to varnish. I realize formulas have changed since then but I think the same still applies. Diesel oils have more additives in them and will probably still do a better job cleaning than any off the shelf cheap conventional oil. Higher dollar synthetics probably do a good job though such as any of the LL01 oils. Standards have really gone up these days on gas oils. As long as you aren't burning a ton of oil, there is no harm in giving it a shot to see how it does. Many thinner diesel oils now too.
Diesel oils are designed to keep contaminants in suspension, well more of them than gasoline engine oils. Any of the european oils are dual rated (diesel and gasoline) if you want to have something for a gasoline engine aswell.
Both diesel and regular oils (for gasoline engines) contain detergents and dispersants. If I understand the differences, diesel oils contain no friction modifiers for "energy conserving" effect. So for cleaning purposes, they're probably about the same. If you're trying to clean up a sludged gas engine, I recommend a few short-interval services with whatever oil is spec'd by the manufacturer. "Maybe" add a few ounces of Marvel Mystery oil (flamesuit on, lol).
My vote goes to high detergent mono grades such as Delo 400 SAE 40 weather permitting above 40F, or SAE 30 above freezing 32F/0C.
Mono grade engine oils are great at cleaning up ring zone deposits too.
Mono grade engine oils are great at cleaning up ring zone deposits too.
diesel oils do have friction modifers and yes have a higher amount od disperents to keep soot suspended.
So will clean faster than a PCMO
So will clean faster than a PCMO
Just for my own understanding, why is this the case?
I believe it is scrubbing action at the molecular level. I've tried SAE 40 on several engines that had ran on 5w30 for years. The engines ran very hot for an hour or two and smelled like something was burning. The oil turned black in a thousand miles in all cases. Engines that have been ran on HDEO's don't exibit that behavior.
SOJ (one user long ago) described that once....if my memory serves well....
....gr I and II monogrades has better cleaning abilities (it has something to do with a sulphur content....)
....gr I and II monogrades has better cleaning abilities (it has something to do with a sulphur content....)
I guess if you have a lot of time and patience to wait for the clean up it might work. I found over the years that if you do in fact have an engine in need of being cleaned up, a product designed for cleaning up an engine is better suited for the job than trying with oil alone and short intervals. My 00 Century was a prime example of that.
What product did you use to clean your Century?
Good luck finding Group I bright stock as the main ingredient in any engine oil these days.......
I'd have to look in my records, it was either Kreen or MMO. I can say TDT 5W40 after about 30K miles didn't do much of anything.
OK I have both Kreen and MMO with Delo XLE 15w40 in the sump
Interesting. Update the threads with your findings if any.
I have had good results using Rotella T6 Multi Vehicle 5w30 which is a HDEO that happens to be rated SN Plus and perfectly fine in gasoline applications.
I'd guess it has to do with aromatic content.
I plan to make a thread in the future. What I said might have sounded confusing. I own both MMO and Kreen (its a few years old but unopened, may need to order more). Currently only Delo 15w40 is in the sump. Towards the end of the OCI will put in some MMO and then try some flushes, whether a large portion of MMO, Rislone, Kreen. I will try them all until the motor is clean and see if the ticking and slapping sounds go away.
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